Subject: [PATCH] Use native format for storing non-transparent pictures.

When using 16-bit color depth for desktop, it is preferable
to also use 16bpp format for images to get better performance.
As an additional bonus, the browser uses less memory when
viewing pages with lots of images.

Taken from https://bugzilla.mozilla.org/show_bug.cgi?id=386440
---
 gfx/thebes/src/gfxPlatformGtk.cpp |   11 +++++++++--
 1 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/gfx/thebes/src/gfxPlatformGtk.cpp b/gfx/thebes/src/gfxPlatformGtk.cpp
index 39e09e7..78e6002 100644
--- a/gfx/thebes/src/gfxPlatformGtk.cpp
+++ b/gfx/thebes/src/gfxPlatformGtk.cpp
@@ -142,8 +142,15 @@ gfxPlatformGtk::CreateOffscreenSurface(const gfxIntSize& size,
 
     if (!UseGlitz()) {
         GdkPixmap* pixmap = nsnull;
-        XRenderPictFormat* xrenderFormat =
-            XRenderFindStandardFormat(display, xrenderFormatID);
+        XRenderPictFormat* xrenderFormat = nsnull;
+
+        if (xrenderFormatID == PictStandardRGB24) {
+            // Actually we want not strictly RGB24, but the fastest non-alpha format 
+            xrenderFormat = XRenderFindVisualFormat(display, GDK_VISUAL_XVISUAL(gdk_visual_get_system()));
+        }
+
+        if (!xrenderFormat)
+            xrenderFormat = XRenderFindStandardFormat(display, xrenderFormatID);
 
         if (!xrenderFormat) {
             // We don't have Render; see if we can just create a pixmap
-- 
1.5.6.5