My laptop, with an ATI card, cannot play tremulous with compiz enabled, and I've always been told that it won't work.
My desktop, a much more powerful machine with an nvidia card, plays compiz and tremulous without lag, slowdown, or any issues whatsoever.
My laptop cannot play tremulous even without compiz. I need to restart the X server without xgl enabled at all. To do that, I run a simple little script,
touch ~/.config/xserver-xgl/disable
When the xserver restarts, it automatically looks for that file and, if it finds it, disables all of the xgl extensions (or whatever they are called)
I then logout, and into fluxbox to play opengl games. really, I need to integrate my script into the session startup files so xgl is disabled/enabled as needed, depending on which desktop I logon to. I haven't bothered with that though.
#!/bin/bash
INPUT=$*
case "$INPUT" in
enable)
rm -f ~/.config/xserver-xgl/disable
echo "You must log out, and then back in"
echo "if XGL is not already enabled"
echo "and you want to enable it"
;;
disable)
touch ~/.config/xserver-xgl/disable
echo "You must log out, and then back in"
echo "if XGL is enabled and you want to"
echo "disable it"
;;
*)
echo "To use this script, type in"
echo "\"xglswitch enable\" to enable XGL"
echo "on your next logon"
echo "or"
echo "\"xglswitch disable\" to disable XGL"
echo "on your next logon"
;;
esac
Its really a simple script, to say the least. It works for me though, and I haven't had the time to play enough games to carry it further.