Could you also add the xorg.conf file? It seems that in the log you're using EXA, and it definitely causes slowdowns. Ideally you should not have anything else in the Device section than the Driver "ati" and the name of the device. Add XAANoOffscreenPixmaps if you want to try out compiz/beryl.
-- [r300] ati driver unuasble slow (full cpu usage just for drawing gtk apps) https://launchpad.net/bugs/90604 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
