I thought I would put in a quick observation about CPU utilization under Beryl (which I assume would be similar for Compiz, maybe incorrectly). As I was wandering through my blog stats, I saw a search entry on “compiz consumes CPU”, so here is my experience in improving graphics performance under beryl:
- Turn off mipmaps.
I updated my system about a couple of weeks ago, and in playing around with the settings for beryl, I decided to try mipmaps. My graphics performance really seemed to take a hit, which translated into a large jump in CPU utilization. I confirmed this when running “glxgears” from konsole. The frame rate was horrible (using an nvidia 7600 GS card, no less) and CPU load was over 90%. After disabling mipmaps in beryl-settings-manager (there are quite a few places where they can be enabled or disabled), frame rates jumped from the low hundreds back to well over 2000 fps and CPU usage dropped to under 15%. Nothing else made such a substantial difference.
Additionally, the level of detail I saw with mipmaps enabled was not readily obvious compared to when they were disabled. So, if your beryl (and maybe compiz) is dogging your graphics when you are sure it shouldn’t, uncheck those mipmap boxes first and see if things don’t improve. By the way, the settings affecting 3d, while seemingly the best place to start when dealing with performance issues, did not make nearly the same difference that disabling mipmaps did – so disable those 3d settings only if you are still not happy with performance. By that time, it might be wise to either look at getting a new card, or stopping the X server and reinstalling your video driver.
Hope this helps!