firefox slowness with xorg 6.9.0

[Tommi Sakari Uimonen]

On Tue, 7 Mar 2006, Michel Dänzer wrote:

> On Tue, 2006-03-07 at 17:39 +0100, Roland Scheidegger wrote:
>> Tommi Sakari Uimonen wrote:
>>> I'm using debian unstable (also tried kanotix), both have xorg 6.9.0 and
>>> kde 3.5. Video card is ATI 7500. Firefox is 1.5
>>>
>>> For reference, I have also oldish gentoo install with xorg 6.8.x and
>>> it's fast. top shows that X takes only about 30% and firefox 50% cpu
>>> while scrolling about:config page with mouse wheel while some other
>>> window is on top of firefox. Gentoo has firefox 1.0.4 and kde 3.4
>>>
>>> I'm just compiling firefox 1.5 to gentoo to bring the two systems
>>> configurations closer to each other. Hopefully I accomplish a situation
>>> where only xorg version differs, and then I really can blame xorg for
>>> the slowness. It could be GTK slowness, because konqueror works fast
>>> with the same setup (same website and another window on top of konqueror)
>> FWIW, I noticed some massive slowdowns when using firefox too recently,
>> but after some digging it seems firefox 1.5 is fully to blame. The
>> slowdowns only happen with firefox 1.5 or seamonkey 1.0, but firefox 1.0
>> is fast. Maybe it simply has to do how it's compiled (using gtk2 and
>> such), I don't know.
>> Some quick profiling showed this however (scrolling on a VERY slow page
>> since it updated its layout, http://www.hardocp.com/):
>> 8608     43.2107  libfb.so                 fbBlt
>> 5168     25.9425  vmlinux                  default_idle
>> 830       4.1665  libgklayout.so           (no symbols)
>> 436       2.1886  Xorg                     (no symbols)
>> 344       1.7268  libxpcom_core.so         (no symbols)
>> 255       1.2801  libfb.so                 fbBltOne
>> 188       0.9437  libmozjs.so              (no symbols)
>> 157       0.7881  libgfx_gtk.so            (no symbols)
>> 153       0.7680  libfb.so                 fbSolid
>> So, firefox 1.5 causes some massive use of libfb.so which firefox 1.0
>> probably didn't (I did not profile firefox 1.0). As to why and how to
>> fix it, no idea... My setup used radeons too if it matters (7200, 9000
>> with xorg 6.9, and a x550 with xorg 6.8.2)
>
> Have you guys tried with EXA? This sounds like the good old 'Cairo and
> XAA don't mix well'. Cairo actually contains a bunch of workarounds for
> XAA, but I think they're disabled with X.Org 6.9 or newer, as it was
> assumed that XAA would get fixed. Also note that GTK+ 2.8.12+ has some
> XAA workarounds again, so if you have an older version, you may want to
> upgrade.

After upgrading the gentoo box to firefox 1.5 (boy that really took some 
time to compile) the slowness came along. So it's firefox 1.5 rendering 
that is slow. I also downgraded the debian system to ff 1.0.7 and it 
became fast. Before downgrading I tried the EXA acceleration, but it 
didn't help. GTK+ version is 2.8.13


Tommi