Whenever I have an OpenGL app running (including GLXGears), certain screen redraw operations will be extremely slow. I can see the display redrawing line by line. This affects the entire screen including the non 3d parts. The 3D accelleration seems to work fine as I can rotate and interact with the 3D parts fine. During the redraw, the CPU untilization goes to 100% on both CPUs.
This is on a FX 5200 Ultra. I did not have this problem with a Geforce 2 GTS. It only happened when I installed the new card.
I've tried both the 5328 and 4496 drivers on kernel 2.4.20-28.9smp.
Usenet thread seems to describe the same problem. Unfortunately, recompiling the kernel interface did not seem to help for me.