diff --git a/common.mk b/common.mk
index ea244cc..4f22609 100644
--- a/common.mk
+++ b/common.mk
@@ -629,7 +629,8 @@ file.$(OBJEXT): {$(VPATH)}file.c $(RUBY_H_INCLUDES) {$(VPATH)}io.h \
 gc.$(OBJEXT): {$(VPATH)}gc.c $(RUBY_H_INCLUDES) {$(VPATH)}re.h \
   {$(VPATH)}regex.h $(ENCODING_H_INCLUDES) $(VM_CORE_H_INCLUDES) \
   {$(VPATH)}gc.h {$(VPATH)}io.h {$(VPATH)}eval_intern.h {$(VPATH)}util.h \
-  {$(VPATH)}debug.h {$(VPATH)}internal.h {$(VPATH)}constant.h
+  {$(VPATH)}debug.h {$(VPATH)}internal.h {$(VPATH)}constant.h \
+  {$(VPATH)}pool_alloc.inc.h {$(VPATH)}pool_alloc.h
 hash.$(OBJEXT): {$(VPATH)}hash.c $(RUBY_H_INCLUDES) {$(VPATH)}util.h \
   $(ENCODING_H_INCLUDES)
 inits.$(OBJEXT): {$(VPATH)}inits.c $(RUBY_H_INCLUDES) \
@@ -692,7 +693,7 @@ signal.$(OBJEXT): {$(VPATH)}signal.c $(RUBY_H_INCLUDES) \
   $(VM_CORE_H_INCLUDES) {$(VPATH)}debug.h
 sprintf.$(OBJEXT): {$(VPATH)}sprintf.c $(RUBY_H_INCLUDES) {$(VPATH)}re.h \
   {$(VPATH)}regex.h {$(VPATH)}vsnprintf.c $(ENCODING_H_INCLUDES)
-st.$(OBJEXT): {$(VPATH)}st.c $(RUBY_H_INCLUDES)
+st.$(OBJEXT): {$(VPATH)}st.c $(RUBY_H_INCLUDES) {$(VPATH)}pool_alloc.h
 strftime.$(OBJEXT): {$(VPATH)}strftime.c $(RUBY_H_INCLUDES) \
   {$(VPATH)}timev.h
 string.$(OBJEXT): {$(VPATH)}string.c $(RUBY_H_INCLUDES) {$(VPATH)}re.h \
diff --git a/configure.in b/configure.in
index 5bc2e4e..b3e60fd 100644
--- a/configure.in
+++ b/configure.in
@@ -1406,7 +1406,8 @@ AC_CHECK_FUNCS(fmod killpg wait4 waitpid fork spawnv syscall __syscall chroot ge
 	      setsid telldir seekdir fchmod cosh sinh tanh log2 round\
 	      setuid setgid daemon select_large_fdset setenv unsetenv\
               mktime timegm gmtime_r clock_gettime gettimeofday poll ppoll\
-              pread sendfile shutdown sigaltstack dl_iterate_phdr)
+              pread sendfile shutdown sigaltstack dl_iterate_phdr \
+	      posix_memalign memalign)
 
 AC_CACHE_CHECK(for unsetenv returns a value, rb_cv_unsetenv_return_value,
   [AC_TRY_COMPILE([
diff --git a/gc.c b/gc.c
index 3238d65..fb8ac5f 100644
--- a/gc.c
+++ b/gc.c
@@ -20,6 +20,7 @@
 #include "vm_core.h"
 #include "internal.h"
 #include "gc.h"
+#include "pool_alloc.h"
 #include "constant.h"
 #include <stdio.h>
 #include <setjmp.h>
@@ -35,6 +36,11 @@
 
 #if defined _WIN32 || defined __CYGWIN__
 #include <windows.h>
+#elif defined POOL_ALLOC_API
+#if   defined(HAVE_POSIX_MEMALIGN)
+#elif defined(HAVE_MEMALIGN)
+#include <malloc.h>
+#endif
 #endif
 
 #ifdef HAVE_VALGRIND_MEMCHECK_H
@@ -311,6 +317,24 @@ struct gc_list {
 
 #define CALC_EXACT_MALLOC_SIZE 0
 
+#ifdef POOL_ALLOC_API
+/* POOL ALLOC API */
+#define POOL_ALLOC_PART 1
+#include "pool_alloc.inc.h"
+#undef POOL_ALLOC_PART
+
+typedef struct pool_layout_t pool_layout_t;
+struct pool_layout_t {
+    pool_header
+      p6,  /* st_table && st_table_entry */
+      p11;  /* st_table.bins init size */
+} pool_layout = {
+    INIT_POOL(void*[6]),
+    INIT_POOL(void*[11])
+};
+static void pool_finalize_header(pool_header *header);
+#endif
+
 typedef struct rb_objspace {
     struct {
 	size_t limit;
@@ -320,6 +344,9 @@ typedef struct rb_objspace {
 	size_t allocations;
 #endif
     } malloc_params;
+#ifdef POOL_ALLOC_API
+    pool_layout_t *pool_headers;
+#endif
     struct {
 	size_t increment;
 	struct heaps_slot *ptr;
@@ -367,7 +394,11 @@ typedef struct rb_objspace {
 static int ruby_initial_gc_stress = 0;
 int *ruby_initial_gc_stress_ptr = &ruby_initial_gc_stress;
 #else
+#  ifdef POOL_ALLOC_API
+static rb_objspace_t rb_objspace = {{GC_MALLOC_LIMIT}, &pool_layout, {HEAP_MIN_SLOTS}};
+#  else
 static rb_objspace_t rb_objspace = {{GC_MALLOC_LIMIT}, {HEAP_MIN_SLOTS}};
+#  endif
 int *ruby_initial_gc_stress_ptr = &rb_objspace.gc_stress;
 #endif
 #define malloc_limit		objspace->malloc_params.limit
@@ -400,6 +431,10 @@ rb_objspace_alloc(void)
     memset(objspace, 0, sizeof(*objspace));
     malloc_limit = initial_malloc_limit;
     ruby_gc_stress = ruby_initial_gc_stress;
+#ifdef POOL_ALLOC_API
+    objspace->pool_headers = (pool_layout_t*) malloc(sizeof(pool_layout));
+    memcpy(objspace->pool_headers, &pool_layout, sizeof(pool_layout));
+#endif
 
     return objspace;
 }
@@ -477,6 +512,13 @@ rb_objspace_free(rb_objspace_t *objspace)
 	heaps_used = 0;
 	heaps = 0;
     }
+#ifdef POOL_ALLOC_API
+    if (objspace->pool_headers) {
+        pool_finalize_header(&objspace->pool_headers->p6);
+        pool_finalize_header(&objspace->pool_headers->p11);
+        free(objspace->pool_headers);
+    }
+#endif
     free(objspace);
 }
 #else
@@ -885,6 +927,27 @@ ruby_xfree(void *x)
 	vm_xfree(&rb_objspace, x);
 }
 
+#ifdef POOL_ALLOC_API
+/* POOL ALLOC API */
+#define POOL_ALLOC_PART 2
+#include "pool_alloc.inc.h"
+#undef POOL_ALLOC_PART
+
+void
+ruby_xpool_free(void *ptr)
+{
+    pool_free_entry((void**)ptr);
+}
+
+#define CONCRET_POOL_MALLOC(pnts) \
+void * ruby_xpool_malloc_##pnts##p () { \
+    return pool_alloc_entry(&rb_objspace.pool_headers->p##pnts ); \
+}
+CONCRET_POOL_MALLOC(6)
+CONCRET_POOL_MALLOC(11)
+#undef CONCRET_POOL_MALLOC
+
+#endif
 
 /*
  *  call-seq:
diff --git a/internal.h b/internal.h
index 172e7f4..11e4d30 100644
--- a/internal.h
+++ b/internal.h
@@ -108,6 +108,8 @@ VALUE rb_iseq_clone(VALUE iseqval, VALUE newcbase);
 
 /* load.c */
 VALUE rb_get_load_path(void);
+void rb_reset_expanded_cache();
+void rb_load_path_ary_push(VALUE path);
 
 /* math.c */
 VALUE rb_math_atan2(VALUE, VALUE);
diff --git a/load.c b/load.c
index 0ff4b60..5d10cc2 100644
--- a/load.c
+++ b/load.c
@@ -4,6 +4,7 @@
 
 #include "ruby/ruby.h"
 #include "ruby/util.h"
+#include "ruby/encoding.h"
 #include "internal.h"
 #include "dln.h"
 #include "eval_intern.h"
@@ -18,6 +19,7 @@ VALUE ruby_dln_librefs;
 #define IS_DLEXT(e) (strcmp((e), DLEXT) == 0)
 #endif
 
+static int sorted_loaded_features = 1;
 
 static const char *const loadable_ext[] = {
     ".rb", DLEXT,
@@ -27,28 +29,44 @@ static const char *const loadable_ext[] = {
     0
 };
 
-VALUE
-rb_get_load_path(void)
-{
-    VALUE load_path = GET_VM()->load_path;
-    return load_path;
-}
+static VALUE rb_checked_expanded_cache(int*);
+static void rb_set_expanded_cache(VALUE, int);
+static VALUE rb_expand_load_paths(long, VALUE*, int*);
+static int cached_expanded_load_path = 1;
 
 VALUE
 rb_get_expanded_load_path(void)
 {
-    VALUE load_path = rb_get_load_path();
-    VALUE ary;
-    long i;
+    VALUE expanded = rb_checked_expanded_cache(NULL);
 
-    ary = rb_ary_new2(RARRAY_LEN(load_path));
-    for (i = 0; i < RARRAY_LEN(load_path); ++i) {
-	VALUE path = rb_file_expand_path(RARRAY_PTR(load_path)[i], Qnil);
-	rb_str_freeze(path);
-	rb_ary_push(ary, path);
+    if ( !RTEST(expanded) ) {
+	VALUE load_path = GET_VM()->load_path;
+	int has_relative = 0;
+
+	if (!load_path) return 0;
+
+	expanded = rb_expand_load_paths(
+			RARRAY_LEN(load_path), RARRAY_PTR(load_path),
+			&has_relative);
+	RB_GC_GUARD(load_path);
+
+	if (cached_expanded_load_path) {
+	    rb_set_expanded_cache(expanded, has_relative);
+	}
+    } else {
+	expanded = rb_ary_dup(expanded);
     }
-    rb_obj_freeze(ary);
-    return ary;
+    return expanded;
+}
+
+VALUE
+rb_get_load_path(void)
+{
+    VALUE load_path =
+	cached_expanded_load_path ?
+	    rb_get_expanded_load_path():
+	    GET_VM()->load_path;
+    return load_path;
 }
 
 static VALUE
@@ -129,6 +147,9 @@ loaded_feature_path_i(st_data_t v, st_data_t b, st_data_t f)
     return ST_STOP;
 }
 
+static long rb_feature_first_equal_or_greater(VALUE, const char *, long);
+static int  rb_stop_search_feature(VALUE, const char *, long);
+
 static int
 rb_feature_p(const char *feature, const char *ext, int rb, int expanded, const char **fn)
 {
@@ -151,8 +172,10 @@ rb_feature_p(const char *feature, const char *ext, int rb, int expanded, const c
 	type = 0;
     }
     features = get_loaded_features();
-    for (i = 0; i < RARRAY_LEN(features); ++i) {
+    i = rb_feature_first_equal_or_greater(features, feature, len);
+    for (; i < RARRAY_LEN(features); ++i) {
 	v = RARRAY_PTR(features)[i];
+	if (rb_stop_search_feature(v, feature, len)) break;
 	f = StringValuePtr(v);
 	if ((n = RSTRING_LEN(v)) < len) continue;
 	if (strncmp(f, feature, len) != 0) {
@@ -176,14 +199,14 @@ rb_feature_p(const char *feature, const char *ext, int rb, int expanded, const c
 	}
     }
     loading_tbl = get_loading_table();
-    if (loading_tbl) {
+    if (loading_tbl && loading_tbl->num_entries > 0) {
 	f = 0;
 	if (!expanded) {
 	    struct loaded_feature_searching fs;
 	    fs.name = feature;
 	    fs.len = len;
 	    fs.type = type;
-	    fs.load_path = load_path ? load_path : rb_get_load_path();
+	    fs.load_path = load_path ? load_path : rb_get_expanded_load_path();
 	    fs.result = 0;
 	    st_foreach(loading_tbl, loaded_feature_path_i, (st_data_t)&fs);
 	    if ((f = fs.result) != 0) {
@@ -251,6 +274,170 @@ rb_feature_provided(const char *feature, const char **loading)
     return FALSE;
 }
 
+static long
+feature_basename_length(const char *feature, long flen)
+{
+    if (sorted_loaded_features) {
+	const char *ext = strrchr(feature, '.');
+	return ext && !strchr(ext, '/') ? ext - feature : flen;
+    } else {
+	return 0;
+    }
+}
+
+static int
+compare_feature_name(const char *left, long llen, const char *right, long rlen)
+{
+    int diff = 0;
+    while (llen-- && rlen--) {
+	diff = left[llen] - right[rlen];
+	if (diff) break;
+	if (left[llen] == '/') break;
+    }
+    return diff;
+}
+
+static int
+rb_compare_feature_name(VALUE loaded, const char *feature, long flen)
+{
+    const char *loaded_name = StringValuePtr(loaded);
+    long loaded_len = feature_basename_length(loaded_name, RSTRING_LEN(loaded));
+    return compare_feature_name(loaded_name, loaded_len, feature, flen);
+}
+
+/* used to find when equal features run out */
+static int
+rb_stop_search_feature(VALUE loaded, const char *feature, long flen)
+{
+    if (sorted_loaded_features)
+	return rb_compare_feature_name(loaded, feature, flen) > 0;
+    else
+	return FALSE;
+}
+
+/* returns first position to search feature from */
+static long
+rb_feature_first_equal_or_greater(VALUE features, const char *feature, long flen)
+{
+    if (sorted_loaded_features) {
+	long before = 0, first = RARRAY_LEN(features);
+	VALUE *values = RARRAY_PTR(features);
+	if (first == 0)
+	    return 0;
+	if (rb_compare_feature_name(values[0], feature, flen) >= 0)
+	    return 0;
+
+	while (first - before > 1) {
+	    long mid = (first + before) / 2;
+	    long cmp = rb_compare_feature_name(values[mid], feature, flen);
+	    if (cmp >= 0)
+		first = mid;
+	    else
+		before = mid;
+	}
+	return first;
+    } else {
+	return 0;
+    }
+}
+
+/* returns position to insert new feature in */
+static long
+rb_feature_first_greater(VALUE features, const char *feature, long flen)
+{
+    if (sorted_loaded_features) {
+	long before = 0, first = RARRAY_LEN(features);
+	VALUE *values = RARRAY_PTR(features);
+	if (first == 0)
+	    return 0;
+	if (rb_compare_feature_name(values[0], feature, flen) > 0)
+	    return 0;
+	if (rb_compare_feature_name(values[first-1], feature, flen) <= 0)
+	    return first;
+
+	while (first - before > 1) {
+	    long mid = (first + before) / 2;
+	    long cmp = rb_compare_feature_name(values[mid], feature, flen);
+	    if (cmp > 0)
+		first = mid;
+	    else
+		before = mid;
+	}
+	return first;
+    } else {
+	return RARRAY_LEN(features);
+    }
+}
+
+
+static VALUE
+rb_push_feature_1(VALUE features, VALUE feature)
+{
+    const char *fname = StringValuePtr(feature);
+    long flen = feature_basename_length(fname, RSTRING_LEN(feature));
+    long i = rb_feature_first_greater(features, fname, flen);
+    rb_ary_push(features, feature);
+    if ( i < RARRAY_LEN(features) - 1 ) {
+	MEMMOVE(RARRAY_PTR(features) + i + 1, RARRAY_PTR(features) + i,
+		VALUE, RARRAY_LEN(features) - i - 1);
+	RARRAY_PTR(features)[i] = feature;
+    }
+    return features;
+}
+
+static VALUE
+rb_push_feature_m(long argc, VALUE *argv, VALUE features)
+{
+    while (argc--) {
+	rb_push_feature_1(features, *argv++);
+    }
+    return features;
+}
+
+static VALUE
+rb_concat_features(VALUE features, VALUE add)
+{
+    add = rb_convert_type(add, T_ARRAY, "Array", "to_ary");
+    if (RARRAY_LEN(add)) {
+	rb_push_feature_m(RARRAY_LEN(add), RARRAY_PTR(add), features);
+    }
+    return features;
+}
+static const char *load_features_undefined_methods[] = {
+    "[]=", "reverse!", "rotate!", "sort!", "sort_by!",
+    "collect!", "map!", "shuffle!", "fill", "insert",
+    NULL
+};
+
+static VALUE
+rb_loaded_features_init(void)
+{
+    char *sorted_flag;
+    const char **name;
+    VALUE loaded_features = rb_ary_new();
+    VALUE loaded_features_c = rb_singleton_class(loaded_features);
+
+    sorted_flag = getenv("RUBY_LOADED_FEATURES_SORTED");
+    if (sorted_flag != NULL) {
+	int sorted_set = atoi(sorted_flag);
+	if (RTEST(ruby_verbose))
+	    fprintf(stderr, "sorted_loaded_features=%d (%d)\n", sorted_set, sorted_loaded_features);
+	sorted_loaded_features = sorted_set;
+    }
+
+    for(name = load_features_undefined_methods; *name; name++) {
+	rb_undef_method(loaded_features_c, *name);
+    }
+
+    if (sorted_loaded_features) {
+	rb_define_method(loaded_features_c, "<<", rb_push_feature_1, 1);
+	rb_define_method(loaded_features_c, "push", rb_push_feature_m, -1);
+	rb_define_method(loaded_features_c, "concat", rb_concat_features, 1);
+	rb_define_method(loaded_features_c, "unshift", rb_push_feature_m, -1);
+    }
+    return loaded_features;
+}
+
 static void
 rb_provide_feature(VALUE feature)
 {
@@ -258,7 +445,10 @@ rb_provide_feature(VALUE feature)
 	rb_raise(rb_eRuntimeError,
 		 "$LOADED_FEATURES is frozen; cannot append feature");
     }
-    rb_ary_push(get_loaded_features(), feature);
+    if (sorted_loaded_features)
+	rb_push_feature_1(get_loaded_features(), feature);
+    else
+	rb_ary_push(get_loaded_features(), feature);
 }
 
 void
@@ -760,6 +950,226 @@ rb_f_autoload_p(VALUE obj, VALUE sym)
     return rb_mod_autoload_p(klass, sym);
 }
 
+/* $LOAD_PATH methods which invalidates cache */
+static const char *load_path_reset_cache_methods[] = {
+    "[]=", "collect!", "compact!", "delete",
+    "delete_if", "fill", "flatten!", "insert", "keep_if",
+    "map!", "reject!", "replace", "select!", "shuffle!",
+    "sort!", "sort_by!", "uniq!", NULL
+};
+
+/* $LOAD_PATH methods which sends also to cache */
+static const char *load_path_apply_to_cache_methods[] = {
+    "clear", "delete_at", "pop", "reverse!", "rotate!",
+    "shift", "slice!", NULL
+};
+
+/* $LOAD_PATH methods which sends to cache whith expanded arguments */
+static const char *load_path_apply_expanded_methods[] = {
+    "<<", "push", "unshift", NULL
+};
+
+void
+rb_reset_expanded_cache()
+{
+    GET_VM()->load_path_expanded_cache = 0;
+}
+
+static VALUE
+rb_load_path_expanded_cache()
+{
+    VALUE cache = GET_VM()->load_path_expanded_cache;
+    VALUE expanded = Qnil;
+    if (RTEST(cache)) {
+	expanded = RARRAY_PTR(cache)[2];
+    }
+    return expanded;
+}
+
+/* Return cache only if we still in the same working directory
+ * and filesystem_encoding didn't change
+ * Invalidate cache otherwise
+ */
+static VALUE
+rb_checked_expanded_cache(int *has_relative)
+{
+    VALUE cache = GET_VM()->load_path_expanded_cache;
+    VALUE expanded = Qnil;
+    if (RTEST(cache)) {
+	VALUE curwd = RARRAY_PTR(cache)[0];
+	VALUE encindex = RARRAY_PTR(cache)[1];
+	int cache_valid = rb_filesystem_encindex() == FIX2INT(encindex);
+
+	if ( cache_valid ) {
+	    cache_valid = curwd == Qtrue;
+	    if (has_relative) {
+		*has_relative = cache_valid;
+	    }
+	    if (!cache_valid ) {
+		char *cwd = my_getcwd();
+		cache_valid = !strcmp(RSTRING_PTR(curwd), cwd);
+		xfree(cwd);
+	    }
+	}
+
+	if ( !cache_valid ) {
+	    rb_reset_expanded_cache();
+	} else {
+	    expanded = RARRAY_PTR(cache)[2];
+	}
+    }
+    RB_GC_GUARD(cache);
+    return expanded;
+}
+
+static void
+rb_set_expanded_cache(VALUE expanded, int has_relative)
+{
+    VALUE cache = rb_ary_new2(3);
+
+    if (has_relative) {
+	char *cwd = my_getcwd();
+	rb_ary_push(cache, rb_str_new_cstr(cwd));
+	xfree(cwd);
+    } else {
+	rb_ary_push(cache, Qtrue);
+    }
+
+    rb_ary_push(cache, INT2FIX(rb_filesystem_encindex()));
+    rb_ary_push(cache, rb_ary_dup(expanded));
+    GET_VM()->load_path_expanded_cache = cache;
+}
+
+static VALUE
+rb_expand_load_paths(long pathc, VALUE* paths, int *has_relative)
+{
+    long i;
+    const char *p;
+    VALUE path, expanded = rb_ary_new2(pathc);
+
+    for(i = 0; i < pathc; i++) {
+	path = rb_get_path(paths[i]);
+	p = RSTRING_PTR(path);
+	*has_relative = *has_relative || !rb_is_absolute_path(p);
+	path = rb_file_expand_path(path, Qnil);
+	rb_str_freeze(path);
+	rb_ary_push(expanded, path);
+    }
+
+    return expanded;
+}
+
+/* Invalidating $LOAD_PATH methods implementation */
+static VALUE
+rb_load_path_reset_cache_method(int argc, VALUE *argv, VALUE self)
+{
+    rb_reset_expanded_cache();
+    return rb_call_super(argc, argv);
+}
+
+/* Proxying $LOAD_PATH methods implementation */
+static VALUE
+rb_load_path_apply_to_cache_method(int argc, VALUE *argv, VALUE self)
+{
+    VALUE load_path_expanded = rb_load_path_expanded_cache();
+    if (RTEST(load_path_expanded)) {
+	ID func = rb_frame_this_func();
+	rb_funcall2(load_path_expanded, func, argc, argv);
+    }
+    return rb_call_super(argc, argv);
+}
+
+/* Proxying with expansion $LOAD_PATH methods implementation */
+static VALUE
+rb_load_path_apply_expanded_method(int argc, VALUE *argv, VALUE self)
+{
+    int old_has_relative = 0;
+    /* We call methods on cache only if we still in the same working directory */
+    VALUE load_path_expanded = rb_checked_expanded_cache(&old_has_relative);
+    if (RTEST(load_path_expanded)) {
+	int has_relative = 0;
+	ID func = rb_frame_this_func();
+	VALUE expanded = rb_expand_load_paths(argc, argv, &has_relative);
+
+	rb_funcall2(load_path_expanded, func, argc, RARRAY_PTR(expanded));
+
+	if (!old_has_relative && has_relative) {
+	    rb_set_expanded_cache(load_path_expanded, has_relative);
+	}
+	RB_GC_GUARD(expanded);
+    }
+    return rb_call_super(argc, argv);
+}
+/* $LOAD_PATH.concat(ary) - special, we call push(*ary) instead
+ * cause I'm lazy a bit and wish not to rewrite method above second time :)
+ */
+static VALUE
+rb_load_path_concat(VALUE self, VALUE ary)
+{
+    ID push;
+    CONST_ID(push, "push");
+    RB_GC_GUARD(ary);
+    return rb_funcall2(self, push, (int)RARRAY_LEN(ary), RARRAY_PTR(ary));
+}
+
+void
+rb_load_path_ary_push(VALUE path)
+{
+    int old_has_relative = 0;
+    VALUE load_path_expanded = rb_checked_expanded_cache(&old_has_relative);
+    if (RTEST(load_path_expanded)) {
+	int has_relative = 0;
+	VALUE expanded = rb_expand_load_paths(1, &path, &has_relative);
+
+	rb_ary_push(load_path_expanded, RARRAY_PTR(expanded)[0]);
+
+	if (!old_has_relative && has_relative) {
+	    rb_set_expanded_cache(load_path_expanded, has_relative);
+	}
+	RB_GC_GUARD(expanded);
+    }
+
+    rb_ary_push(GET_VM()->load_path, path);
+}
+
+static VALUE
+rb_load_path_init(void)
+{
+    const char **name;
+    VALUE load_path = rb_ary_new();
+    char *cached_flag;
+
+    cached_flag = getenv("RUBY_CACHED_LOAD_PATH");
+    if (cached_flag != NULL) {
+	cached_expanded_load_path = atoi(cached_flag);
+    }
+
+    /* Do all the magick if user did not disable it
+     * with RUBY_CACHED_LOAD_PATH=0 environment variable
+     */
+    if (cached_expanded_load_path) {
+	VALUE load_path_c = rb_singleton_class(load_path);
+
+	for(name = load_path_reset_cache_methods; *name; name++ ) {
+	    rb_define_method(load_path_c, *name, rb_load_path_reset_cache_method, -1);
+	}
+
+	for(name = load_path_apply_to_cache_methods; *name; name++ ) {
+	    rb_define_method(load_path_c, *name, rb_load_path_apply_to_cache_method, -1);
+	}
+
+	for(name = load_path_apply_expanded_methods; *name; name++ ) {
+	    rb_define_method(load_path_c, *name, rb_load_path_apply_expanded_method, -1);
+	}
+
+	rb_define_method(load_path_c, "concat", rb_load_path_concat, 1);
+    }
+
+    rb_reset_expanded_cache();
+
+    return load_path;
+}
+
 void
 Init_load()
 {
@@ -772,11 +1182,11 @@ Init_load()
     rb_define_hooked_variable(var_load_path, (VALUE*)vm, load_path_getter, rb_gvar_readonly_setter);
     rb_alias_variable(rb_intern("$-I"), id_load_path);
     rb_alias_variable(rb_intern("$LOAD_PATH"), id_load_path);
-    vm->load_path = rb_ary_new();
+    vm->load_path = rb_load_path_init();
 
     rb_define_virtual_variable("$\"", get_loaded_features, 0);
     rb_define_virtual_variable("$LOADED_FEATURES", get_loaded_features, 0);
-    vm->loaded_features = rb_ary_new();
+    vm->loaded_features = rb_loaded_features_init();
 
     rb_define_global_function("load", rb_f_load, -1);
     rb_define_global_function("require", rb_f_require, 1);
diff --git a/pool_alloc.h b/pool_alloc.h
new file mode 100644
index 0000000..957708e
--- /dev/null
+++ b/pool_alloc.h
@@ -0,0 +1,11 @@
+#ifndef POOL_ALLOC_H
+#define POOL_ALLOC_H
+
+#define POOL_ALLOC_API
+#ifdef POOL_ALLOC_API
+void  ruby_xpool_free(void *ptr);
+void *ruby_xpool_malloc_6p();
+void *ruby_xpool_malloc_11p();
+#endif
+
+#endif
diff --git a/pool_alloc.inc.h b/pool_alloc.inc.h
new file mode 100644
index 0000000..5b735be
--- /dev/null
+++ b/pool_alloc.inc.h
@@ -0,0 +1,187 @@
+/*
+ * this is generic pool allocator
+ * you should define following macroses:
+ * ITEM_NAME - unique identifier, which allows to hold functions in a namespace
+ * ITEM_TYPEDEF(name) - passed to typedef to localize item type
+ * free_entry - desired name of function for free entry
+ * alloc_entry - defired name of function for allocate entry
+ */
+
+#if POOL_ALLOC_PART == 1
+#define DEFAULT_POOL_SIZE 8192
+typedef unsigned int pool_holder_counter;
+
+typedef struct pool_entry_list pool_entry_list;
+typedef struct pool_holder pool_holder;
+
+typedef struct pool_header {
+    pool_holder         *first;
+    pool_holder         *_black_magick;
+    pool_holder_counter  size; // size of entry in sizeof(void*) items
+    pool_holder_counter  total; // size of entry in sizeof(void*) items
+} pool_header;
+
+struct pool_holder {
+    pool_holder_counter free, total;
+    pool_header  *header;
+    void               *freep;
+    pool_holder        *fore, *back;
+    void *data[1];
+};
+#define POOL_DATA_SIZE(pool_size) (((pool_size) - sizeof(void*) * 6 - offsetof(pool_holder, data)) / sizeof(void*))
+#define POOL_ENTRY_SIZE(item_type) ((sizeof(item_type) - 1) / sizeof(void*) + 1)
+#define POOL_HOLDER_COUNT(pool_size, item_type) (POOL_DATA_SIZE(pool_size)/POOL_ENTRY_SIZE(item_type))
+#define INIT_POOL(item_type) {NULL, NULL, POOL_ENTRY_SIZE(item_type), POOL_HOLDER_COUNT(DEFAULT_POOL_SIZE, item_type)}
+
+#elif POOL_ALLOC_PART == 2
+static void *
+aligned_malloc(size_t alignment, size_t size)
+{
+    void *res;
+
+#if __MINGW32__
+    res = __mingw_aligned_malloc(size, alignment);
+#elif _WIN32 || defined __CYGWIN__
+    res = _aligned_malloc(size, alignment);
+#elif defined(HAVE_POSIX_MEMALIGN)
+    if (posix_memalign(&res, alignment, size) == 0) {
+        return res;
+    } else {
+        return NULL;
+    }
+#elif defined(HAVE_MEMALIGN)
+    res = memalign(alignment, size);
+#else
+#error no memalign function
+#endif
+    return res;
+}
+
+static void
+aligned_free(void *ptr)
+{
+#if __MINGW32__
+    __mingw_aligned_free(ptr);
+#elif _WIN32 || defined __CYGWIN__
+    _aligned_free(ptr);
+#else
+    free(ptr);
+#endif
+}
+
+static pool_holder *
+pool_holder_alloc(pool_header *header)
+{
+    pool_holder *holder;
+    pool_holder_counter i, size, count;
+    register void **ptr;
+
+    size_t sz = offsetof(pool_holder, data) +
+	    header->size * header->total * sizeof(void*);
+#define objspace (&rb_objspace)
+    vm_malloc_prepare(objspace, DEFAULT_POOL_SIZE);
+    if (header->first != NULL) return header->first;
+    TRY_WITH_GC(holder = (pool_holder*) aligned_malloc(DEFAULT_POOL_SIZE, sz));
+    malloc_increase += DEFAULT_POOL_SIZE;
+#if CALC_EXACT_MALLOC_SIZE
+    objspace->malloc_params.allocated_size += DEFAULT_POOL_SIZE;
+    objspace->malloc_params.allocations++;
+#endif
+#undef objspace
+
+    size = header->size;
+    count = header->total;
+    holder->free = count;
+    holder->total = count;
+    holder->header = header;
+    holder->fore = NULL;
+    holder->back = NULL;
+    holder->freep = &holder->data;
+    ptr = holder->data;
+    for(i = count - 1; i; i-- ) {
+	ptr = *ptr = ptr + size;
+    }
+    *ptr = NULL;
+    header->first = holder;
+    return holder;
+}
+
+static inline void
+pool_holder_unchaing(pool_header *header, pool_holder *holder)
+{
+    register pool_holder *fore = holder->fore, *back = holder->back;
+    holder->fore = NULL;
+    holder->back = NULL;
+    if (fore != NULL)  fore->back     = back;
+    else               header->_black_magick = back;
+    if (back != NULL)  back->fore     = fore;
+    else               header->first = fore;
+}
+
+static inline pool_holder *
+entry_holder(void **entry)
+{
+    return (pool_holder*)(((uintptr_t)entry) & ~(DEFAULT_POOL_SIZE - 1));
+}
+
+static inline void
+pool_free_entry(void **entry)
+{
+    pool_holder *holder = entry_holder(entry);
+    pool_header *header = holder->header;
+
+    if (holder->free++ == 0) {
+	register pool_holder *first = header->first;
+	if (first == NULL) {
+	    header->first = holder;
+	} else {
+	    holder->back = first;
+	    holder->fore = first->fore;
+	    first->fore = holder;
+	    if (holder->fore)
+		holder->fore->back = holder;
+	    else
+		header->_black_magick = holder;
+	}
+    } else if (holder->free == holder->total && header->first != holder ) {
+	pool_holder_unchaing(header, holder);
+	aligned_free(holder);
+#if CALC_EXACT_MALLOC_SIZE
+	rb_objspace.malloc_params.allocated_size -= DEFAULT_POOL_SIZE;
+	rb_objspace.malloc_params.allocations--;
+#endif
+	return;
+    }
+
+    *entry = holder->freep;
+    holder->freep = entry;
+}
+
+static inline void*
+pool_alloc_entry(pool_header *header)
+{
+    pool_holder *holder = header->first;
+    void **result;
+    if (holder == NULL) {
+	holder = pool_holder_alloc(header);
+    }
+
+    result = holder->freep;
+    holder->freep = *result;
+
+    if (--holder->free == 0) {
+	pool_holder_unchaing(header, holder);
+    }
+
+    return result;
+}
+
+static void
+pool_finalize_header(pool_header *header)
+{
+    if (header->first) {
+        aligned_free(header->first);
+        header->first = NULL;
+    }
+}
+#endif
diff --git a/ruby.c b/ruby.c
index b53784f..0897400 100644
--- a/ruby.c
+++ b/ruby.c
@@ -209,7 +209,6 @@ push_include(const char *path, VALUE (*filter)(VALUE))
 {
     const char sep = PATH_SEP_CHAR;
     const char *p, *s;
-    VALUE load_path = GET_VM()->load_path;
 
     p = path;
     while (*p) {
@@ -217,7 +216,7 @@ push_include(const char *path, VALUE (*filter)(VALUE))
 	    p++;
 	if (!*p) break;
 	for (s = p; *s && *s != sep; s = CharNext(s));
-	rb_ary_push(load_path, (*filter)(rubylib_mangled_path(p, s - p)));
+	rb_load_path_ary_push((*filter)(rubylib_mangled_path(p, s - p)));
 	p = s;
     }
 }
@@ -338,7 +337,6 @@ ruby_init_loadpath(void)
 void
 ruby_init_loadpath_safe(int safe_level)
 {
-    VALUE load_path;
     ID id_initial_load_path_mark;
     extern const char ruby_initial_load_paths[];
     const char *paths = ruby_initial_load_paths;
@@ -438,7 +436,6 @@ ruby_init_loadpath_safe(int safe_level)
 #define RUBY_RELATIVE(path, len) rubylib_mangled_path((path), (len))
 #define PREFIX_PATH() RUBY_RELATIVE(exec_prefix, sizeof(exec_prefix)-1)
 #endif
-    load_path = GET_VM()->load_path;
 
     if (safe_level == 0) {
 #ifdef MANGLED_PATH
@@ -452,7 +449,7 @@ ruby_init_loadpath_safe(int safe_level)
 	size_t len = strlen(paths);
 	VALUE path = RUBY_RELATIVE(paths, len);
 	rb_ivar_set(path, id_initial_load_path_mark, path);
-	rb_ary_push(load_path, path);
+	rb_load_path_ary_push(path);
 	paths += len + 1;
     }
 
@@ -1349,6 +1346,7 @@ process_options(int argc, char **argv, struct cmdline_options *opt)
 	for (i = 0; i < RARRAY_LEN(load_path); ++i) {
 	    rb_enc_associate(RARRAY_PTR(load_path)[i], lenc);
 	}
+	rb_reset_expanded_cache();
     }
     if (!(opt->disable & DISABLE_BIT(gems))) {
 #if defined DISABLE_RUBYGEMS && DISABLE_RUBYGEMS
diff --git a/st.c b/st.c
index ba21b31..ed16995 100644
--- a/st.c
+++ b/st.c
@@ -7,6 +7,7 @@
 #include "st.h"
 #else
 #include "ruby/ruby.h"
+#include "pool_alloc.h"
 #endif
 
 #include <stdio.h>
@@ -27,6 +28,9 @@ struct st_table_entry {
 
 #define ST_DEFAULT_MAX_DENSITY 5
 #define ST_DEFAULT_INIT_TABLE_SIZE 11
+#define ST_DEFAULT_SECOND_TABLE_SIZE 19
+#define ST_DEFAULT_PACKED_TABLE_SIZE 18
+#define MAX_PACKED_HASH (ST_DEFAULT_PACKED_TABLE_SIZE / 3)
 
     /*
      * DEFAULT_MAX_DENSITY is the default for the largest we allow the
@@ -61,20 +65,98 @@ static void rehash(st_table *);
 #ifdef RUBY
 #define malloc xmalloc
 #define calloc xcalloc
+#define realloc xrealloc
 #define free(x) xfree(x)
 #endif
 
 #define numberof(array) (int)(sizeof(array) / sizeof((array)[0]))
 
-#define alloc(type) (type*)malloc((size_t)sizeof(type))
-#define Calloc(n,s) (char*)calloc((n),(s))
-
 #define EQUAL(table,x,y) ((x)==(y) || (*(table)->type->compare)((x),(y)) == 0)
 
 /* remove cast to unsigned int in the future */
 #define do_hash(key,table) (unsigned int)(st_index_t)(*(table)->type->hash)((key))
 #define do_hash_bin(key,table) (do_hash((key), (table))%(table)->num_bins)
 
+/* preparation for possible allocation improvements */
+#ifdef POOL_ALLOC_API
+#define st_alloc_entry() (st_table_entry *)ruby_xpool_malloc_6p()
+#define st_free_entry(entry) ruby_xpool_free(entry)
+#define st_alloc_table() (st_table *)ruby_xpool_malloc_6p()
+#define st_dealloc_table(table) ruby_xpool_free(table)
+static inline st_table_entry **
+st_alloc_bins(st_index_t size)
+{
+    st_table_entry **result;
+    if (size == 11) {
+        result = (st_table_entry **) ruby_xpool_malloc_11p();
+        memset(result, 0, 11 * sizeof(st_table_entry *));
+    }
+    else
+        result = (st_table_entry **) ruby_xcalloc(size, sizeof(st_table_entry*));
+    return result;
+}
+static inline void
+st_free_bins(st_table_entry **bins, st_index_t size)
+{
+    if (size == 11)
+	ruby_xpool_free(bins);
+    else
+	ruby_xfree(bins);
+}
+static inline st_table_entry**
+st_realloc_bins(st_table_entry **bins, st_index_t newsize, st_index_t oldsize)
+{
+    st_free_bins(bins, oldsize);
+    return st_alloc_bins(newsize);
+}
+#else
+#define st_alloc_entry() (st_table_entry *)malloc(sizeof(st_table_entry))
+#define st_free_entry(entry) free(entry)
+#define st_alloc_table() (st_table *)malloc(sizeof(st_table))
+#define st_dealloc_table(table) free(table)
+#define st_alloc_bins(size) (st_table_entry **)calloc(size, sizeof(st_table_entry *))
+#define st_free_bins(bins, size) free(bins)
+static inline st_table_entry**
+st_realloc_bins(st_table_entry **bins, st_index_t newsize, st_index_t oldsize)
+{
+    bins = (st_table_entry **) realloc(bins, newsize * sizeof(st_table_entry *));
+    memset(bins, 0, newsize * sizeof(st_table_entry *));
+    return bins;
+}
+#endif
+
+/* preparation for possible packing improvements */
+#define PKEY_POS(i, num_bins) ((num_bins)-(i)*2-2)
+#define PVAL_POS(i, num_bins) ((num_bins)-(i)*2-1)
+#define PHASH_POS(i, num_bins) (i)
+#define PKEY(table, i) (st_data_t)(table)->bins[PKEY_POS(i, (table)->num_bins)]
+#define PVAL(table, i) (st_data_t)(table)->bins[PVAL_POS(i, (table)->num_bins)]
+#define PHASH(table, i) (st_data_t)(table)->bins[PHASH_POS(i, (table)->num_bins)]
+#define PKEY_SET(table, i, v) do{ (table)->bins[PKEY_POS(i, (table)->num_bins)] = (st_table_entry *)(v); } while(0)
+#define PVAL_SET(table, i, v) do{ (table)->bins[PVAL_POS(i, (table)->num_bins)] = (st_table_entry *)(v); } while(0)
+#define PHASH_SET(table, i, v) do{ (table)->bins[PHASH_POS(i, (table)->num_bins)] = (st_table_entry *)(v); } while(0)
+/* this function depends much on packed layout, so that it placed here */
+static inline void
+remove_packed_entry(st_table *table, st_index_t i)
+{
+    table->num_entries--;
+    if (i < table->num_entries) {
+        st_index_t mv = table->num_entries - i, upto = table->num_bins - 2*table->num_entries;
+        memmove(table->bins + i, table->bins + i + 1, sizeof(st_table_entry *) * mv);
+        memmove(table->bins + upto, table->bins + upto - 2,
+                sizeof(st_table_entry *) * mv * 2);
+    }
+}
+/* ultra packed values */
+#define MAX_ULTRA_PACKED 1
+#define ULTRA_PACKED(table) ((table)->num_bins == 0)
+#define UPHASH(table) ((st_index_t)(table)->bins)
+#define UPKEY(table)  ((st_data_t)(table)->head)
+#define UPVAL(table)  ((st_data_t)(table)->tail)
+#define UPHASH_SET(table, val) do{ (table)->bins = (st_table_entry **)(val); } while(0)
+#define UPKEY_SET(table, val) do{ (table)->head = (st_table_entry *)(val); } while(0)
+#define UPVAL_SET(table, val) do{ (table)->tail = (st_table_entry *)(val); } while(0)
+
 /*
  * MINSIZE is the minimum size of a dictionary.
  */
@@ -85,8 +167,8 @@ static void rehash(st_table *);
 Table of prime numbers 2^n+a, 2<=n<=30.
 */
 static const unsigned int primes[] = {
-	8 + 3,
-	16 + 3,
+	ST_DEFAULT_INIT_TABLE_SIZE,
+	ST_DEFAULT_SECOND_TABLE_SIZE,
 	32 + 5,
 	64 + 3,
 	128 + 3,
@@ -161,8 +243,6 @@ stat_col(void)
 }
 #endif
 
-#define MAX_PACKED_NUMHASH (ST_DEFAULT_INIT_TABLE_SIZE/2)
-
 st_table*
 st_init_table_with_size(const struct st_hash_type *type, st_index_t size)
 {
@@ -181,14 +261,19 @@ st_init_table_with_size(const struct st_hash_type *type, st_index_t size)
     }
 #endif
 
-    size = new_size(size);	/* round up to prime number */
 
-    tbl = alloc(st_table);
+    tbl = st_alloc_table();
     tbl->type = type;
     tbl->num_entries = 0;
-    tbl->entries_packed = type == &type_numhash && size/2 <= MAX_PACKED_NUMHASH;
+    if ( (tbl->entries_packed = size <= MAX_PACKED_HASH) ) {
+	size = size <= MAX_ULTRA_PACKED ? 0 :
+		ST_DEFAULT_PACKED_TABLE_SIZE;
+    }
+    else {
+	size = new_size(size);	/* round up to prime number */
+    }
     tbl->num_bins = size;
-    tbl->bins = (st_table_entry **)Calloc(size, sizeof(st_table_entry*));
+    tbl->bins = size ? st_alloc_bins(size) : NULL;
     tbl->head = 0;
     tbl->tail = 0;
 
@@ -253,7 +338,7 @@ st_clear(st_table *table)
 	table->bins[i] = 0;
 	while (ptr != 0) {
 	    next = ptr->next;
-	    free(ptr);
+	    st_free_entry(ptr);
 	    ptr = next;
 	}
     }
@@ -266,8 +351,9 @@ void
 st_free_table(st_table *table)
 {
     st_clear(table);
-    free(table->bins);
-    free(table);
+    if (table->num_bins)
+	st_free_bins(table->bins, table->num_bins);
+    st_dealloc_table(table);
 }
 
 size_t
@@ -306,40 +392,69 @@ count_collision(const struct st_hash_type *type)
 #define FOUND_ENTRY
 #endif
 
-#define FIND_ENTRY(table, ptr, hash_val, bin_pos) do {\
-    (bin_pos) = (hash_val)%(table)->num_bins;\
-    (ptr) = (table)->bins[(bin_pos)];\
-    FOUND_ENTRY;\
-    if (PTR_NOT_EQUAL((table), (ptr), (hash_val), key)) {\
-	COLLISION;\
-	while (PTR_NOT_EQUAL((table), (ptr)->next, (hash_val), key)) {\
-	    (ptr) = (ptr)->next;\
-	}\
-	(ptr) = (ptr)->next;\
-    }\
-} while (0)
+static st_table_entry *
+find_entry(st_table *table, st_data_t key, st_index_t hash_val, st_index_t bin_pos)
+{
+    register st_table_entry *ptr = table->bins[bin_pos];
+    FOUND_ENTRY;
+    if (PTR_NOT_EQUAL(table, ptr, hash_val, key)) {
+	COLLISION;
+	while (PTR_NOT_EQUAL(table, ptr->next, hash_val, key)) {
+	    ptr = ptr->next;
+	}
+	ptr = ptr->next;
+    }
+    return ptr;
+}
+
+static inline st_index_t
+find_packed_index(st_table *table, st_index_t hash_val, st_data_t key)
+{
+    st_index_t i = 0;
+    for(;;) {
+        while (i < table->num_entries && PHASH(table, i) != hash_val) i++;
+        if (i == table->num_entries || EQUAL(table, key, PKEY(table, i)))
+            break;
+        i++;
+    }
+    return i;
+}
+
+static inline int
+check_ultra_packed(st_table *table, st_index_t hash_val, st_data_t key)
+{
+  return table->num_entries && UPHASH(table) == hash_val &&
+      EQUAL(table, key, UPKEY(table));
+}
 
 #define collision_check 0
 
 int
 st_lookup(st_table *table, register st_data_t key, st_data_t *value)
 {
-    st_index_t hash_val, bin_pos;
+    st_index_t hash_val;
     register st_table_entry *ptr;
 
+    hash_val = do_hash(key, table);
+
     if (table->entries_packed) {
-        st_index_t i;
-        for (i = 0; i < table->num_entries; i++) {
-            if ((st_data_t)table->bins[i*2] == key) {
-                if (value !=0) *value = (st_data_t)table->bins[i*2+1];
-                return 1;
-            }
-        }
+	if (ULTRA_PACKED(table)) {
+	    if (check_ultra_packed(table, hash_val, key)) {
+		if (value != 0) *value = UPVAL(table);
+		return 1;
+	    }
+	}
+	else {
+	    st_index_t i = find_packed_index(table, hash_val, key);
+	    if (i < table->num_entries) {
+		if (value != 0) *value = PVAL(table, i);
+		return 1;
+	    }
+	}
         return 0;
     }
 
-    hash_val = do_hash(key, table);
-    FIND_ENTRY(table, ptr, hash_val, bin_pos);
+    ptr = find_entry(table, key, hash_val, hash_val % table->num_bins);
 
     if (ptr == 0) {
 	return 0;
@@ -353,22 +468,29 @@ st_lookup(st_table *table, register st_data_t key, st_data_t *value)
 int
 st_get_key(st_table *table, register st_data_t key, st_data_t *result)
 {
-    st_index_t hash_val, bin_pos;
+    st_index_t hash_val;
     register st_table_entry *ptr;
 
+    hash_val = do_hash(key, table);
+
     if (table->entries_packed) {
-        st_index_t i;
-        for (i = 0; i < table->num_entries; i++) {
-            if ((st_data_t)table->bins[i*2] == key) {
-                if (result !=0) *result = (st_data_t)table->bins[i*2];
-                return 1;
-            }
-        }
+	if (ULTRA_PACKED(table)) {
+	    if (check_ultra_packed(table, hash_val, key)) {
+		if (result != 0) *result = UPKEY(table);
+		return 1;
+	    }
+	}
+	else {
+	    st_index_t i = find_packed_index(table, hash_val, key);
+	    if (i < table->num_entries) {
+		if (result != 0) *result = PKEY(table, i);
+		return 1;
+	    }
+	}
         return 0;
     }
 
-    hash_val = do_hash(key, table);
-    FIND_ENTRY(table, ptr, hash_val, bin_pos);
+    ptr = find_entry(table, key, hash_val, hash_val % table->num_bins);
 
     if (ptr == 0) {
 	return 0;
@@ -382,85 +504,160 @@ st_get_key(st_table *table, register st_data_t key, st_data_t *result)
 #undef collision_check
 #define collision_check 1
 
-#define MORE_PACKABLE_P(table) \
-    ((st_index_t)((table)->num_entries+1) * 2 <= (table)->num_bins && \
-     (table)->num_entries+1 <= MAX_PACKED_NUMHASH)
-
-#define ADD_DIRECT(table, key, value, hash_val, bin_pos)\
-do {\
-    st_table_entry *entry;\
-    if ((table)->num_entries > ST_DEFAULT_MAX_DENSITY * (table)->num_bins) {\
-	rehash(table);\
-        (bin_pos) = (hash_val) % (table)->num_bins;\
-    }\
-    \
-    entry = alloc(st_table_entry);\
-    \
-    entry->hash = (hash_val);\
-    entry->key = (key);\
-    entry->record = (value);\
-    entry->next = (table)->bins[(bin_pos)];\
-    if ((table)->head != 0) {\
-	entry->fore = 0;\
-	(entry->back = (table)->tail)->fore = entry;\
-	(table)->tail = entry;\
-    }\
-    else {\
-	(table)->head = (table)->tail = entry;\
-	entry->fore = entry->back = 0;\
-    }\
-    (table)->bins[(bin_pos)] = entry;\
-    (table)->num_entries++;\
-} while (0)
+static inline st_table_entry *
+new_entry(st_table * table, st_data_t key, st_data_t value,
+	st_index_t hash_val, register st_index_t bin_pos)
+{
+    register st_table_entry *entry = st_alloc_entry();
+
+    entry->next = table->bins[bin_pos];
+    table->bins[bin_pos] = entry;
+    entry->hash = hash_val;
+    entry->key = key;
+    entry->record = value;
+
+    return entry;
+}
+
+static inline void
+add_direct(st_table * table, st_data_t key, st_data_t value,
+	st_index_t hash_val, register st_index_t bin_pos)
+{
+    register st_table_entry *entry;
+    if (table->num_entries > ST_DEFAULT_MAX_DENSITY * table->num_bins) {
+	rehash(table);
+        bin_pos = hash_val % table->num_bins;
+    }
+
+    entry = new_entry(table, key, value, hash_val, bin_pos);
+
+    if (table->head != 0) {
+	entry->fore = 0;
+	(entry->back = table->tail)->fore = entry;
+	table->tail = entry;
+    }
+    else {
+	table->head = table->tail = entry;
+	entry->fore = entry->back = 0;
+    }
+    table->num_entries++;
+}
 
 static void
 unpack_entries(register st_table *table)
 {
     st_index_t i;
-    struct st_table_entry *packed_bins[MAX_PACKED_NUMHASH*2];
+    register st_table_entry *entry;
+#if ST_DEFAULT_INIT_TABLE_SIZE == ST_DEFAULT_PACKED_TABLE_SIZE
+    struct st_table_entry *packed_bins[ST_DEFAULT_INIT_TABLE_SIZE];
     st_table tmp_table = *table;
 
-    memcpy(packed_bins, table->bins, sizeof(struct st_table_entry *) * table->num_entries*2);
+    memcpy(packed_bins, table->bins, sizeof(st_table_entry *) * ST_DEFAULT_INIT_TABLE_SIZE);
     table->bins = packed_bins;
     tmp_table.entries_packed = 0;
     tmp_table.num_entries = 0;
     memset(tmp_table.bins, 0, sizeof(struct st_table_entry *) * tmp_table.num_bins);
-    for (i = 0; i < table->num_entries; i++) {
-        st_insert(&tmp_table, (st_data_t)packed_bins[i*2], (st_data_t)packed_bins[i*2+1]);
+#else
+    st_table tmp_table = {table->type, 0, 0, 0, 0, 0, 0};
+
+    tmp_table.bins = st_alloc_bins(ST_DEFAULT_INIT_TABLE_SIZE);
+    tmp_table.num_bins = ST_DEFAULT_INIT_TABLE_SIZE;
+#endif
+    entry = new_entry(&tmp_table, PKEY(table, 0), PVAL(table, 0),
+	    PHASH(table, 0), PHASH(table, 0) % tmp_table.num_bins);
+    tmp_table.head = entry;
+    entry->back = 0;
+    for (i = 1; i < MAX_PACKED_HASH; i++) {
+	register st_table_entry *oldentry = entry;
+	st_index_t hash_val = PHASH(table, i);
+	entry = new_entry(&tmp_table, PKEY(table, i), PVAL(table, i),
+		hash_val, hash_val % tmp_table.num_bins);
+	oldentry->fore = entry;
+	entry->back = oldentry;
     }
+    entry->fore = 0;
+    tmp_table.tail = entry;
+    tmp_table.num_entries = MAX_PACKED_HASH;
+#if ST_DEFAULT_INIT_TABLE_SIZE != ST_DEFAULT_PACKED_TABLE_SIZE
+    st_free_bins(table->bins, table->num_bins);
+#endif
     *table = tmp_table;
 }
 
+static void
+add_packed_direct(st_table *table, st_data_t key, st_data_t value, st_index_t hash_val)
+{
+    if (table->num_entries < MAX_PACKED_HASH ) {
+	st_index_t i = table->num_entries++;
+	PKEY_SET(table, i, key);
+	PVAL_SET(table, i, value);
+	PHASH_SET(table, i, hash_val);
+    }
+    else {
+	unpack_entries(table);
+	add_direct(table, key, value, hash_val, hash_val % table->num_bins);
+    }
+}
+
+static void
+add_upacked_direct(st_table *table, st_data_t key, st_data_t value, st_index_t hash_val)
+{
+    if (table->num_entries) {
+	st_index_t fhash = UPHASH(table);
+	st_data_t fkey = UPKEY(table), fval = UPVAL(table);
+	table->bins = st_alloc_bins(ST_DEFAULT_PACKED_TABLE_SIZE);
+	table->num_bins = ST_DEFAULT_PACKED_TABLE_SIZE;
+	PHASH_SET(table, 0, fhash);
+	PKEY_SET(table, 0, fkey);
+	PVAL_SET(table, 0, fval);
+	PHASH_SET(table, 1, hash_val);
+	PKEY_SET(table, 1, key);
+	PVAL_SET(table, 1, value);
+	table->num_entries = 2;
+	table->head = NULL;
+	table->tail = NULL;
+    }
+    else {
+	UPHASH_SET(table, hash_val);
+	UPKEY_SET(table, key);
+	UPVAL_SET(table, value);
+	table->num_entries = 1;
+    }
+}
+
 int
 st_insert(register st_table *table, register st_data_t key, st_data_t value)
 {
-    st_index_t hash_val, bin_pos;
+    st_index_t hash_val;
+    register st_index_t bin_pos;
     register st_table_entry *ptr;
 
+    hash_val = do_hash(key, table);
+
     if (table->entries_packed) {
-        st_index_t i;
-        for (i = 0; i < table->num_entries; i++) {
-            if ((st_data_t)table->bins[i*2] == key) {
-                table->bins[i*2+1] = (struct st_table_entry*)value;
-                return 1;
-            }
-        }
-        if (MORE_PACKABLE_P(table)) {
-            i = table->num_entries++;
-            table->bins[i*2] = (struct st_table_entry*)key;
-            table->bins[i*2+1] = (struct st_table_entry*)value;
-            return 0;
-        }
-        else {
-            unpack_entries(table);
-        }
+	if (ULTRA_PACKED(table)) {
+	    if (check_ultra_packed(table, hash_val, key)) {
+		UPVAL_SET(table, value);
+		return 1;
+	    }
+	    add_upacked_direct(table, key, value, hash_val);
+	}
+	else {
+	    st_index_t i = find_packed_index(table, hash_val, key);
+	    if (i < table->num_entries) {
+		PVAL_SET(table, i, value);
+		return 1;
+	    }
+	    add_packed_direct(table, key, value, hash_val);
+	}
+	return 0;
     }
 
-    hash_val = do_hash(key, table);
-    FIND_ENTRY(table, ptr, hash_val, bin_pos);
+    bin_pos = hash_val % table->num_bins;
+    ptr = find_entry(table, key, hash_val, bin_pos);
 
     if (ptr == 0) {
-	ADD_DIRECT(table, key, value, hash_val, bin_pos);
+	add_direct(table, key, value, hash_val, bin_pos);
 	return 0;
     }
     else {
@@ -473,34 +670,39 @@ int
 st_insert2(register st_table *table, register st_data_t key, st_data_t value,
 	   st_data_t (*func)(st_data_t))
 {
-    st_index_t hash_val, bin_pos;
+    st_index_t hash_val;
+    register st_index_t bin_pos;
     register st_table_entry *ptr;
 
+    hash_val = do_hash(key, table);
+
     if (table->entries_packed) {
-        st_index_t i;
-        for (i = 0; i < table->num_entries; i++) {
-            if ((st_data_t)table->bins[i*2] == key) {
-                table->bins[i*2+1] = (struct st_table_entry*)value;
-                return 1;
-            }
-        }
-        if (MORE_PACKABLE_P(table)) {
-            i = table->num_entries++;
-            table->bins[i*2] = (struct st_table_entry*)key;
-            table->bins[i*2+1] = (struct st_table_entry*)value;
-            return 0;
-        }
-        else {
-            unpack_entries(table);
-        }
+	if (ULTRA_PACKED(table)) {
+	    if (check_ultra_packed(table, hash_val, key)) {
+		UPVAL_SET(table, value);
+		return 1;
+	    }
+	    key = (*func)(key);
+	    add_upacked_direct(table, key, value, hash_val);
+	}
+	else {
+	    st_index_t i = find_packed_index(table, hash_val, key);
+	    if (i < table->num_entries) {
+		PVAL_SET(table, i, value);
+		return 1;
+	    }
+	    key = (*func)(key);
+	    add_packed_direct(table, key, value, hash_val);
+	}
+	return 0;
     }
 
-    hash_val = do_hash(key, table);
-    FIND_ENTRY(table, ptr, hash_val, bin_pos);
+    bin_pos = hash_val % table->num_bins;
+    ptr = find_entry(table, key, hash_val, bin_pos);
 
     if (ptr == 0) {
 	key = (*func)(key);
-	ADD_DIRECT(table, key, value, hash_val, bin_pos);
+	add_direct(table, key, value, hash_val, bin_pos);
 	return 0;
     }
     else {
@@ -512,36 +714,30 @@ st_insert2(register st_table *table, register st_data_t key, st_data_t value,
 void
 st_add_direct(st_table *table, st_data_t key, st_data_t value)
 {
-    st_index_t hash_val, bin_pos;
+    st_index_t hash_val;
 
+    hash_val = do_hash(key, table);
     if (table->entries_packed) {
-        int i;
-        if (MORE_PACKABLE_P(table)) {
-            i = table->num_entries++;
-            table->bins[i*2] = (struct st_table_entry*)key;
-            table->bins[i*2+1] = (struct st_table_entry*)value;
-            return;
-        }
-        else {
-            unpack_entries(table);
-        }
+	if (ULTRA_PACKED(table)) {
+	    add_upacked_direct(table, key, value, hash_val);
+	}
+	else {
+	    add_packed_direct(table, key, value, hash_val);
+	}
+	return;
     }
 
-    hash_val = do_hash(key, table);
-    bin_pos = hash_val % table->num_bins;
-    ADD_DIRECT(table, key, value, hash_val, bin_pos);
+    add_direct(table, key, value, hash_val, hash_val % table->num_bins);
 }
 
 static void
 rehash(register st_table *table)
 {
     register st_table_entry *ptr, **new_bins;
-    st_index_t i, new_num_bins, hash_val;
+    st_index_t new_num_bins, hash_val;
 
     new_num_bins = new_size(table->num_bins+1);
-    new_bins = (st_table_entry**)
-	xrealloc(table->bins, new_num_bins * sizeof(st_table_entry*));
-    for (i = 0; i < new_num_bins; ++i) new_bins[i] = 0;
+    new_bins = st_realloc_bins(table->bins, new_num_bins, table->num_bins);
     table->num_bins = new_num_bins;
     table->bins = new_bins;
 
@@ -562,17 +758,20 @@ st_copy(st_table *old_table)
     st_index_t num_bins = old_table->num_bins;
     st_index_t hash_val;
 
-    new_table = alloc(st_table);
+    new_table = st_alloc_table();
     if (new_table == 0) {
 	return 0;
     }
 
     *new_table = *old_table;
-    new_table->bins = (st_table_entry**)
-	Calloc((unsigned)num_bins, sizeof(st_table_entry*));
+    if (ULTRA_PACKED(old_table)) {
+	return new_table;
+    }
+
+    new_table->bins = st_alloc_bins(num_bins);
 
     if (new_table->bins == 0) {
-	free(new_table);
+	st_dealloc_table(new_table);
 	return 0;
     }
 
@@ -585,7 +784,7 @@ st_copy(st_table *old_table)
 	prev = 0;
 	tail = &new_table->head;
 	do {
-	    entry = alloc(st_table_entry);
+	    entry = st_alloc_entry();
 	    if (entry == 0) {
 		st_free_table(new_table);
 		return 0;
@@ -604,21 +803,22 @@ st_copy(st_table *old_table)
     return new_table;
 }
 
-#define REMOVE_ENTRY(table, ptr) do					\
-    {									\
-	if ((ptr)->fore == 0 && (ptr)->back == 0) {			\
-	    (table)->head = 0;						\
-	    (table)->tail = 0;						\
-	}								\
-	else {								\
-	    st_table_entry *fore = (ptr)->fore, *back = (ptr)->back;	\
-	    if (fore) fore->back = back;				\
-	    if (back) back->fore = fore;				\
-	    if ((ptr) == (table)->head) (table)->head = fore;		\
-	    if ((ptr) == (table)->tail) (table)->tail = back;		\
-	}								\
-	(table)->num_entries--;						\
-    } while (0)
+static inline void
+remove_entry(st_table *table, st_table_entry *ptr)
+{
+    if (ptr->fore == 0 && ptr->back == 0) {
+	table->head = 0;
+	table->tail = 0;
+    }
+    else {
+	st_table_entry *fore = ptr->fore, *back = ptr->back;
+	if (fore) fore->back = back;
+	if (back) back->fore = fore;
+	if (ptr == table->head) table->head = fore;
+	if (ptr == table->tail) table->tail = back;
+    }
+    table->num_entries--;
+}
 
 int
 st_delete(register st_table *table, register st_data_t *key, st_data_t *value)
@@ -627,30 +827,37 @@ st_delete(register st_table *table, register st_data_t *key, st_data_t *value)
     st_table_entry **prev;
     register st_table_entry *ptr;
 
+    hash_val = do_hash(*key, table);
+
     if (table->entries_packed) {
-        st_index_t i;
-        for (i = 0; i < table->num_entries; i++) {
-            if ((st_data_t)table->bins[i*2] == *key) {
-                if (value != 0) *value = (st_data_t)table->bins[i*2+1];
-                table->num_entries--;
-                memmove(&table->bins[i*2], &table->bins[(i+1)*2],
-                        sizeof(struct st_table_entry*) * 2*(table->num_entries-i));
-                return 1;
-            }
-        }
+	if (ULTRA_PACKED(table)) {
+	    if (check_ultra_packed(table, hash_val, *key)) {
+		if (value != 0) *value = UPVAL(table);
+		*key = UPKEY(table);
+		table->num_entries = 0;
+		return 1;
+	    }
+	}
+	else {
+	    st_index_t i = find_packed_index(table, hash_val, *key);
+	    if (i < table->num_entries) {
+		if (value != 0) *value = PVAL(table, i);
+		*key = PKEY(table, i);
+		remove_packed_entry(table, i);
+		return 1;
+	    }
+	}
         if (value != 0) *value = 0;
         return 0;
     }
 
-    hash_val = do_hash_bin(*key, table);
-
-    for (prev = &table->bins[hash_val]; (ptr = *prev) != 0; prev = &ptr->next) {
+    for (prev = &table->bins[hash_val % table->num_bins]; (ptr = *prev) != 0; prev = &ptr->next) {
 	if (EQUAL(table, *key, ptr->key)) {
 	    *prev = ptr->next;
-	    REMOVE_ENTRY(table, ptr);
+	    remove_entry(table, ptr);
 	    if (value != 0) *value = ptr->record;
 	    *key = ptr->key;
-	    free(ptr);
+	    st_free_entry(ptr);
 	    return 1;
 	}
     }
@@ -665,12 +872,25 @@ st_delete_safe(register st_table *table, register st_data_t *key, st_data_t *val
     st_index_t hash_val;
     register st_table_entry *ptr;
 
+    hash_val = do_hash(*key, table);
+
     if (table->entries_packed) {
-	st_index_t i;
-	for (i = 0; i < table->num_entries; i++) {
-	    if ((st_data_t)table->bins[i*2] == *key) {
-		if (value != 0) *value = (st_data_t)table->bins[i*2+1];
-		table->bins[i*2] = (void *)never;
+	if (ULTRA_PACKED(table)) {
+	    if (check_ultra_packed(table, hash_val, *key)) {
+		if (value != 0) *value = UPVAL(table);
+		*key = UPKEY(table);
+		UPKEY_SET(table, never);
+		UPHASH_SET(table, 0);
+		return 1;
+	    }
+	}
+	else {
+	    st_index_t i = find_packed_index(table, hash_val, *key);
+	    if (i < table->num_entries) {
+		if (value != 0) *value = PVAL(table, i);
+		*key = PKEY(table, i);
+		PKEY_SET(table, i, never);
+		PHASH_SET(table, i,  0);
 		return 1;
 	    }
 	}
@@ -678,12 +898,11 @@ st_delete_safe(register st_table *table, register st_data_t *key, st_data_t *val
 	return 0;
     }
 
-    hash_val = do_hash_bin(*key, table);
-    ptr = table->bins[hash_val];
+    ptr = table->bins[hash_val % table->num_bins];
 
     for (; ptr != 0; ptr = ptr->next) {
 	if ((ptr->key != never) && EQUAL(table, ptr->key, *key)) {
-	    REMOVE_ENTRY(table, ptr);
+	    remove_entry(table, ptr);
 	    *key = ptr->key;
 	    if (value != 0) *value = ptr->record;
 	    ptr->key = ptr->record = never;
@@ -702,17 +921,25 @@ st_cleanup_safe(st_table *table, st_data_t never)
     st_index_t i;
 
     if (table->entries_packed) {
-	st_index_t i = 0, j = 0;
-	while ((st_data_t)table->bins[i*2] != never) {
-	    if (i++ == table->num_entries) return;
+	if (ULTRA_PACKED(table)) {
+	    if (UPKEY(table) == never) {
+		table->num_entries = 0;
+	    }
 	}
-	for (j = i; ++i < table->num_entries;) {
-	    if ((st_data_t)table->bins[i*2] == never) continue;
-	    table->bins[j*2] = table->bins[i*2];
-	    table->bins[j*2+1] = table->bins[i*2+1];
-	    j++;
+	else {
+	    st_index_t i = 0, j = 0;
+	    while (PKEY(table, i) != never) {
+		if (i++ == table->num_entries) return;
+	    }
+	    for (j = i; ++i < table->num_entries;) {
+		if (PKEY(table, i) == never) continue;
+		PKEY_SET(table, j,  PKEY(table, i));
+		PVAL_SET(table, j,  PVAL(table, i));
+		PHASH_SET(table, j,  PHASH(table, i));
+		j++;
+	    }
+	    table->num_entries = j;
 	}
-	table->num_entries = j;
 	return;
     }
 
@@ -722,7 +949,7 @@ st_cleanup_safe(st_table *table, st_data_t never)
 	    if (ptr->key == never) {
 		tmp = ptr;
 		*last = ptr = ptr->next;
-		free(tmp);
+		st_free_entry(tmp);
 	    }
 	    else {
 		ptr = *(last = &ptr->next);
@@ -736,23 +963,51 @@ st_foreach(st_table *table, int (*func)(ANYARGS), st_data_t arg)
 {
     st_table_entry *ptr, **last, *tmp;
     enum st_retval retval;
-    st_index_t i;
+    st_index_t i = 0;
 
     if (table->entries_packed) {
-        for (i = 0; i < table->num_entries; i++) {
-            st_index_t j;
-            st_data_t key, val;
-            key = (st_data_t)table->bins[i*2];
-            val = (st_data_t)table->bins[i*2+1];
+	st_index_t hash;
+	st_data_t key, val;
+	if (ULTRA_PACKED(table) && table->num_entries) {
+	    key = UPKEY(table);
+	    val = UPVAL(table);
+	    hash = UPHASH(table);
+	    retval = (*func)(key, val, arg);
+	    if (!ULTRA_PACKED(table)) goto packed;
+	    switch(retval) {
+	      case ST_CHECK:
+		if (UPKEY(table) == Qundef && UPHASH(table) == 0)
+		    break;
+		if (table->num_entries && UPHASH(table) == hash &&
+			EQUAL(table, key, UPKEY(table)))
+		    break;
+		retval = (*func)(0, 0, arg, 1);
+		return 1;
+	      case ST_CONTINUE:
+		break;
+	      case ST_STOP:
+		return 0;
+	      case ST_DELETE:
+		table->num_entries = 0;
+	    }
+	    return 0;
+	}
+        for (; i < table->num_entries; i++) {
+            key = PKEY(table, i);
+            val = PVAL(table, i);
+            hash = PHASH(table,i);
             retval = (*func)(key, val, arg);
+	packed:
 	    if (!table->entries_packed) goto unpacked;
             switch (retval) {
 	      case ST_CHECK:	/* check if hash is modified during iteration */
-                for (j = 0; j < table->num_entries; j++) {
-                    if ((st_data_t)table->bins[j*2] == key)
-                        break;
-                }
-                if (j == table->num_entries) {
+		/* work around uncomforming befaviour of hash */
+		if (PKEY(table, i) == Qundef && PHASH(table, i) == 0)
+		    break;
+		else if (i < table->num_entries &&
+			PHASH(table, i) == hash && EQUAL(table, key, PKEY(table, i)))
+		    break;
+                if (find_packed_index(table, hash, key) == table->num_entries) {
                     /* call func with error notice */
                     retval = (*func)(0, 0, arg, 1);
                     return 1;
@@ -763,9 +1018,7 @@ st_foreach(st_table *table, int (*func)(ANYARGS), st_data_t arg)
 	      case ST_STOP:
 		return 0;
 	      case ST_DELETE:
-                table->num_entries--;
-                memmove(&table->bins[i*2], &table->bins[(i+1)*2],
-                        sizeof(struct st_table_entry*) * 2*(table->num_entries-i));
+		remove_packed_entry(table, i);
                 i--;
                 break;
             }
@@ -773,9 +1026,10 @@ st_foreach(st_table *table, int (*func)(ANYARGS), st_data_t arg)
         return 0;
       unpacked:
 	ptr = table->head;
-	while (i-- > 0) {
-	    if (!(ptr = ptr->fore)) return 0;
-	}
+	for(;ptr && i; i--, ptr = ptr->fore) {}
+	if (ptr == 0) return retval == ST_CHECK ? 1 : 0;
+	i = ptr->hash % table->num_bins;
+	goto check_retval;
     }
     else {
 	ptr = table->head;
@@ -785,6 +1039,7 @@ st_foreach(st_table *table, int (*func)(ANYARGS), st_data_t arg)
 	do {
 	    i = ptr->hash % table->num_bins;
 	    retval = (*func)(ptr->key, ptr->record, arg);
+check_retval:
 	    switch (retval) {
 	      case ST_CHECK:	/* check if hash is modified during iteration */
 		for (tmp = table->bins[i]; tmp != ptr; tmp = tmp->next) {
@@ -806,8 +1061,8 @@ st_foreach(st_table *table, int (*func)(ANYARGS), st_data_t arg)
 		    if (ptr == tmp) {
 			tmp = ptr->fore;
 			*last = ptr->next;
-			REMOVE_ENTRY(table, ptr);
-			free(ptr);
+			remove_entry(table, ptr);
+			st_free_entry(ptr);
 			if (ptr == tmp) return 0;
 			ptr = tmp;
 			break;
@@ -829,18 +1084,21 @@ st_reverse_foreach(st_table *table, int (*func)(ANYARGS), st_data_t arg)
 
     if (table->entries_packed) {
         for (i = table->num_entries-1; 0 <= i; i--) {
-            int j;
+            int hash;
             st_data_t key, val;
-            key = (st_data_t)table->bins[i*2];
-            val = (st_data_t)table->bins[i*2+1];
+            key = PKEY(table, i);
+            val = PVAL(table, i);
+            hash = PHASH(table, i);
             retval = (*func)(key, val, arg);
             switch (retval) {
 	      case ST_CHECK:	/* check if hash is modified during iteration */
-                for (j = 0; j < table->num_entries; j++) {
-                    if ((st_data_t)table->bins[j*2] == key)
-                        break;
-                }
-                if (j == table->num_entries) {
+		/* work around uncomforming befaviour of hash */
+		if (PKEY(table, i) == Qundef && PHASH(table, i) == 0)
+		    break;
+		else if (i < table->num_entries &&
+			PHASH(table, i) == hash && EQUAL(table, key, PKEY(table, i)))
+		    break;
+                if (find_packed_index(table, hash, key) == table->num_entries) {
                     /* call func with error notice */
                     retval = (*func)(0, 0, arg, 1);
                     return 1;
@@ -851,9 +1109,7 @@ st_reverse_foreach(st_table *table, int (*func)(ANYARGS), st_data_t arg)
 	      case ST_STOP:
 		return 0;
 	      case ST_DELETE:
-                table->num_entries--;
-                memmove(&table->bins[i*2], &table->bins[(i+1)*2],
-                        sizeof(struct st_table_entry*) * 2*(table->num_entries-i));
+		remove_packed_entry(table, i);
                 break;
             }
         }
@@ -886,8 +1142,8 @@ st_reverse_foreach(st_table *table, int (*func)(ANYARGS), st_data_t arg)
 		    if (ptr == tmp) {
 			tmp = ptr->back;
 			*last = ptr->next;
-			REMOVE_ENTRY(table, ptr);
-			free(ptr);
+			remove_entry(table, ptr);
+			st_free_entry(ptr);
 			ptr = tmp;
 			break;
 		    }
diff --git a/vm.c b/vm.c
index 2d7e15c..d1fe744 100644
--- a/vm.c
+++ b/vm.c
@@ -1575,6 +1575,7 @@ rb_vm_mark(void *ptr)
 	RUBY_MARK_UNLESS_NULL(vm->thgroup_default);
 	RUBY_MARK_UNLESS_NULL(vm->mark_object_ary);
 	RUBY_MARK_UNLESS_NULL(vm->load_path);
+	RUBY_MARK_UNLESS_NULL(vm->load_path_expanded_cache);
 	RUBY_MARK_UNLESS_NULL(vm->loaded_features);
 	RUBY_MARK_UNLESS_NULL(vm->top_self);
 	RUBY_MARK_UNLESS_NULL(vm->coverages);
diff --git a/vm_core.h b/vm_core.h
index 0dda1c4..f4dc58a 100644
--- a/vm_core.h
+++ b/vm_core.h
@@ -298,6 +298,7 @@ typedef struct rb_vm_struct {
     /* load */
     VALUE top_self;
     VALUE load_path;
+    VALUE load_path_expanded_cache;
     VALUE loaded_features;
     struct st_table *loading_table;