I asked for help in the ubuntu forums: http://ubuntuforums.org/showthread.php?t=267836
As suggested there, in addition to he options I already added, I put these also into my xorg.conf Option "DRI" "true" Option "ColorTiling" "on" Option "EnablePageFlip" "true" Option "AccelMethod" "EXA" So my device section looks like that: Section "Device" Identifier "ATI Technologies, Inc. M24 1P [Radeon Mobility X600]" Driver "radeon" BusID "PCI:1:0:0" Option "NoAccel" "false" Option "AGPMode" "8" Option "AGPFastWrite" "on" Option "DRI" "true" Option "ColorTiling" "on" Option "EnablePageFlip" "true" Option "AccelMethod" "EXA" EndSection With this config everything works well! -- Very bad performance with X600 in Edgy https://launchpad.net/bugs/62768 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs