Comment 4 for bug 252094

I have now found a workaround for the issue.

I think it basically is to do with the upgrade from XAA to EXA acceleration.

EXA appears not be working with the Intel GMA 965 (GM) chipset (including the Intel X3100).

Upon editing my xorg.conf file to add references to XAA I now have better performance, and am able to use KDE4 desktop effects.

In particular, under Section Device, I added:

 Option "XaaNoPixmapCache"
 Option "XAANoOffscreenPixmaps" "1"
 Option "DRI" "true"
 Option "AccelMethod" "XAA"

and also

 VideoRam 440320
 Option "XvMCSurfaces" "6"
 Option "May_Need_ForceBIOS" "1"

but not sure if these last three items are necessary.