RV350, compositing and horrible performance.
I probably best ask some opinions here, before bombarding the ML with this.
I have an ancient laptop, that's still going strong. An IBM T42. This is a 2004 model. It spurts a fast 2.1 GHz Pentium-M and boasts a whopping 2 GiB of ram. There's a pretty fast 32 GiB SLC IDE-SSD in it and the onboard GPU, a Radeon 9600, features 64 MiB dedicated videoram. While yes, it's almost 10 years old, it works really well and runs pretty fast/fast enough.
Last week I've updated to Ubuntu Gnome 13.04 which features Gnome 3.6 that I upgraded to 3.8. All works well, except I find the video performance appalling. Now I understand very well that it is very old, and r300 architecture is quite dated. I also was able to play 3D games on it (a heavy 3D game via wine for example does about 7-15 FPS, but it worked well) before.
With the new Gnome the desktop is supposedly fully hardware accelerated (e.g. composited). However things are just really slow, with the CPU sitting at its low ondemand setting mostly, so it's not the CPU being over stressed. Things like opening the 'dash' or is it 'activities' I believe it's called? takes almost 1 to 2 seconds to render. Alt-tab is also equally slow. Dragging a window around however seems fast enough.
So where to start looking, or is the rv350 really that old that compositing desktops sucks, while 3D applications work fine. Personally I'm more thinking of blaming Gnome, since I think even 3.6 doesn't work composited on ati blobs on more recent hardware, but maybe there's something else amiss.