Performance change from X in Fedora Core 4 to Fedora Core 5

[Roo]

Machine: Athlon XP 2000+

Graphics card: Matrox G550 (AGP, 32Mb).

Distro: Fedora Core 5

This machine used to run Fedora Core 4 and the graphics, while still being
slow compared to stuff under Windows, were tolerable. After upgrading to
Fedora Core 5, things seem to become almost unbearably slow -- GTK apps in
particular became even more sluggish than they usually are. I strongly
suspect the introduction of Cairo (and the change to GTK to use it
exclusively), but obviously I can't prove that since there is no facility
to tell GTK not to use Cairo and test it. All of the claimed performance
improvements in the FC5's version of GNOME were sucked up by this change,
and more. It's now slower than ever -- you can practically see the window
contents redrawing. This PC can dual boot with Windows XP, and the
difference is embarrassing.

Performance is the elephant in the room when it comes to GTK... so
discussing it with GTK developers is a pointless task. However, I would
like to know from X developers: has there been a serious performance
regression in the support for Matrox cards? Has the RENDER extension lost
much of its hardware support under these cards in the FC5 version of xorg?
Or is Cairo just really slow?

Are only Intel motherboard chipsets, ATI and NVIDIA cards getting
attention these days?