Re: Poor 2D Performance
Check again. I'm getting great results with the 256 series drivers. Also, you can mitigate the slowdowns by ensuring that the following options are DISABLED (one of them aggravates the leak, the other one replicates functionality present in the NVIDIA driver)
Option "TripleBuffer" "on" #it must be off
Option "BackingStore" "on" #ditto
Also, play with KWin settings. My best results are with Direct Rendering enabled. KDE 4.5 has done a serious bugfixing with that mode, and KDE 4.6 is set to revamp their entire compositing engine.