With KMS enabled on my Radeon 4870 X2, scrolling up and down in Firefox is extremely slow. Konqueror and Chromium do not have the same issues. Disabling KMS without changing anything else fixes the issue entirely.
Can you try with the latest changes in xf86-video-ati git?
Yeah, I'm on the latest now, just updated. Still really slow. Happens regardless of kwin's video output, even with compositing off.
I do have the same problem with the following:
kernel 2.6.33 with xorg 1.8, mesa 7.8.1, libdrm 2.4.20 and
xf86-video-ati 6.13.0 (on Archlinux and the xorg18 repo that packages all of
this except kernel which is in the core repo).
I have the problem with Firefox but not with Konqueror for example.
I will attach my dmesg and xorg.log.
Created attachment 35131 [details]
dmesg, xorg 1.8, kernel 2.6.33, mesa 7.8.1, libdrm 2.4.20, xf86-video-ati 6.13.0, KMS enabled
Created attachment 35132 [details]
Xorg.0.log, xorg 1.8, kernel 2.6.33, mesa 7.8.1, libdrm 2.4.20, xf86-video-ati 6.13.0, KMS enabled
I can also confirm that with KMS disabled, there is no such problem.
(In reply to comment #6)
> I can also confirm that with KMS disabled, there is no such problem.
And I can confirm I am seeing bug 27627 when KMS is disabled (not as much as with the laptop I used to report bug 27691 :)
*** This bug has been marked as a duplicate of bug 27284 ***