Comment 8 for bug 416001

It certainly kills performance for me. glxgears goes down from 1200 to 30 !!!
(I know that it is not a scientific measure, but it does reflect the dramatic change of feel.)
maybe there is another option which would fix the problem without killing performance.

b.t.w. there is another bug which seems to be the same as this:
https://bugs.launchpad.net/ubuntu/+source/xorg/+bug/440904