I have a two years old laptop (AMD, firstname.lastname@example.orgGhz) which video card is not supported by any driver (ATI radeon X1200).
On Precise, it ran with Unity 2D. It was not really fast, but it was usable.
I tested Quantal (latest daily-live) and I found that the desktop was not usable.
- the opening/closing animation of a window or menu takes 3 seconds each time
- opening the dash takes around 5 seconds
- moving windows is horribly jerky
- when idle (just with a terminal and a top), compiz eat ~8% of the CPU
AFAIK, compiz supports degrading the user experience according to the computer capabilities.
So why not applying a custom profile to llvmpipe to disable menu fade in/out, windows animations, blur and/or transparency?
Such (supposedly) simple changes could boost FPS quite a bit and lead weak computers to be usable again in this use case.
I could not test myself because ccsm is no longer available in Quantal (I don't know how to tweak Compiz/Unity without it).