Comment 78 for bug 760814

I'm not sure all the bugs described here are the same.
The one I'm experiencing seems to only be related to "moving" things around (icons on the desktop, windows) and glxgears. When I enable woobly windows, the animation is fast, cube rotation seems fast too. Disabling OpenGL makes icons/windows moves fast again. Re-enabling OpenGL with no addition (no cube, no woobly windows, etc.) get back to sluggish mode.
I'm not using Unity but Gnome Classic session.

GLXgears symptoms are strange : when I run it, the gears are not turning though I get "34905 frames in 5.0 seconds = 6980.985 FPS". This message does not come up every 5 seconds as it should but "sometimes" between 5 and 15 secs I would say. Also, I noticed that when I hover the mouse over the window decorations (size grip, title, window borders) I get much more frequent screen refreshes. When glxgears is running, the whole computer is much much less responsive, the fan makes more noise... Like if part of the calculation was not handled by the gfx card but by the main processor itself (Core I7). Top shows (when it gets updated, not every 3 seconds as it should) glxgears and Xorg taking up 100% CPU time and compiz takes 40%.
NVidia GeForce GTS 240 with driver nvidia-current 270.41.06-0ubuntu1.
Let me know if I can be of any help solving this issue.