[Dapper] [X.org] Slow rendering/high CPU usage on ATI MACH 64

[ajkessel]

I recently switched an HP Omnibook 600 (Pentium III 700MHz 384M RAM ATI
Mach 64) from Debian Sarge to Ubuntu Dapper.



With Debian Sarge, running xserver-xfree86, windows rendered fine. The
system was usable and responsive.



With Ubuntu Dapper (X11), alt-tab switching windows is noticeably
slower, even when nothing else is going on. For example, with just a
Firefox and Terminal window open and nothing going on in either way,
alt-tabbing is painful. top also shows Xorg regularly using up > 50%
CPU, which wasn't true in Debian Sarge.



I've read elsewhere that hald sometimes slows down Dapper systems
looking for CD-ROM devices, but killing all hald processes makes no
difference. DRI acceleration is not enable (but shouldn't need to be
for desktop drawing); XVideo works fine (probably irrelevant).



Nothing suspicious shows up in dmesg.



I've upgraded all packages.



Any ideas how to troubleshoot?


-- 
ajkessel