A bit of "shot in the black", but give it a try. Change the following option in xorg.conf from EXA to XAA or the other way round.
I remember a friend of mine having a similar problem with pidgin's notification bubble, and this is what he did. His 2d perfomance became a bit slower, so he needed 2 more options to make it faster again. All that on a es1000 with the radeon driver.
So, from "man radeon"
Code:
Option "AccelMethod" "string"
Chooses between available acceleration architectures. Valid
options are XAA and EXA. XAA is the traditional acceleration
architecture and support for it is very stable. EXA is a newer
acceleration architecture with better performance for the Render
and Composite extensions, but the rendering code for it is newer
and possibly unstable. The default is XAA.