Ardour3/Windows Gdk + Cairo performance hack -- http://gareus.org/wiki/ardour_windows_gdk_and_cairo

ardour_3.5-3386-gec92524.patch

diff --git a/libs/canvas/canvas.cc b/libs/canvas/canvas.cc
index 133e094..cbedcd1 100644
--- a/libs/canvas/canvas.cc
+++ b/libs/canvas/canvas.cc
@@ -727,7 +727,10 @@ GtkCanvas::item_going_away (Item* item, boost::optional<Rect> bounding_box)
 bool
 GtkCanvas::on_expose_event (GdkEventExpose* ev)
 {
+	static int on = 1;
 	Cairo::RefPtr<Cairo::Context> cairo_context = get_window()->create_cairo_context ();
+	cairo_surface_t *sf = cairo_context->get_group_target()->cobj();
+	cairo_surface_set_user_data(sf, (const cairo_user_data_key_t *) 0xb17b17, &on , NULL);
 	render (Rect (ev->area.x, ev->area.y, ev->area.x + ev->area.width, ev->area.y + ev->area.height), cairo_context);
 	return true;
 }
diff --git a/libs/gtkmm2ext/fastmeter.cc b/libs/gtkmm2ext/fastmeter.cc
index 3d28253..ed969ec 100644
--- a/libs/gtkmm2ext/fastmeter.cc
+++ b/libs/gtkmm2ext/fastmeter.cc
@@ -553,6 +553,9 @@ FastMeter::horizontal_size_allocate (Gtk::Allocation &alloc)
 void
 FastMeter::render (cairo_t* cr, cairo_rectangle_t* area)
 {
+	static int on = 1;
+	cairo_surface_t *sf = cairo_get_group_target(cr);
+	cairo_surface_set_user_data(sf, (const cairo_user_data_key_t *) 0xb17b17, &on , NULL);
 	if (orientation == Vertical) {
 		return vertical_expose (cr, area);
 	} else {

cairo_1.14.0_bitblit.patch

--- a/cairo-1.14.0/src/win32/cairo-win32-display-surface.c	2013-08-29 06:04:28.000000000 +0200
+++ c/cairo-1.14.0/src/win32/cairo-win32-display-surface.c	2014-10-26 20:24:56.412990453 +0100
@@ -455,23 +455,38 @@
 	surface->fallback =
 	    _cairo_win32_display_surface_create_for_dc (surface->win32.dc,
 							surface->win32.format,
 							surface->win32.extents.width,
 							surface->win32.extents.height);
+
+#if 1 // XXX rg
+	fprintf(stderr, "NEW fallback surf %dx%d for surf=%d (%s)\n",
+			surface->win32.extents.width, surface->win32.extents.height,
+			surface->win32.base.unique_id,
+			cairo_surface_get_user_data(surface, (const cairo_user_data_key_t *)0xb17b17) ? "noblit" : "blit"
+			);
+#endif
+
 	if (unlikely (status = surface->fallback->status))
 	    goto err;
 
+#if 1 // XXX rg
+	if (!cairo_surface_get_user_data(surface, (const cairo_user_data_key_t *)0xb17b17)) {
+#endif
 	if (!BitBlt (to_win32_surface(surface->fallback)->dc,
 		     0, 0,
 		     surface->win32.extents.width,
 		     surface->win32.extents.height,
 		     surface->win32.dc,
 		     0, 0,
 		     SRCCOPY)) {
 	    status = _cairo_error (CAIRO_STATUS_DEVICE_ERROR);
 	    goto err;
 	}
+#if 1 // XXX rg
+	}
+#endif
     }
 
     surface = to_win32_display_surface (surface->fallback);
 done:
     GdiFlush();