Untested patch to speed up certain transliterations by ~25%

trans-fast.patch

diff --git a/src/core/Str.pm b/src/core/Str.pm
index c0c886a..3590fbe 100644
--- a/src/core/Str.pm
+++ b/src/core/Str.pm
@@ -1081,10 +1081,9 @@ my class Str does Stringy { # declared in BOOTSTRAP
         }
 
         multi method triage_substitution($_ where { .key ~~ Cool }) {
-            return unless defined index($!source, .key, $!index);
-            self.compare_substitution($_,
-                                      index($!source, .key, $!index),
-                                      .key.chars);
+            my $pos := index($!source, .key, $!index);
+            return unless defined $pos;
+            self.compare_substitution($_, $pos, .key.chars);
         }
 
         multi method triage_substitution($_) {