The problem: ppracer flickers very badly, with about half of the screen at a time being "blacked out". It looks as if ppracer were trying to synchronize with the video cards refresh rate but were failing miserably. The graphics is so bad that I am unable to read the frame rate which appears at the side of the screen.

Now the background of the problem:

I have recently apt-get dist-upgraded my X server to xorg 7.0.22 in Debian Testing. After a little tweaking I was able to get DRI and 3D acceleration back to work--sort of. All games have become significantly slower, albeit not like software rendering. I would estimate that on average frame rates have dropped by about 15~20%. By adding LIBGL_DEBUG=verbose to my environment I get the following messages when I start any OpenGL app:

libGL warning: 3D driver claims to not support visual 0x23
libGL warning: 3D driver claims to not support visual 0x25
libGL warning: 3D driver claims to not support visual 0x27
libGL warning: 3D driver claims to not support visual 0x29
libGL warning: 3D driver claims to not support visual 0x2b
libGL warning: 3D driver claims to not support visual 0x2d
libGL warning: 3D driver claims to not support visual 0x2f
libGL warning: 3D driver claims to not support visual 0x31

I have never seen glxgears run slower than it does now, but it no longer prints the frame rates to its stdout/stderr, so I am unable to quote a frame rate value. Yet, I know that hardware acceleration is happening because glxgears is not hogging the processor. I have tried using ppracer like a blind man, and the responsiveness is acceptable, which again indicates that hardware acceleration is taking place.

This flicker is not an issue with other games such as supertux, chromium, gl-117 and armagetron. It is an issue with both ppracer 0.3.1-7 in Debian Testing (Etch) and ppracer 0.5alpha from projects.planetpenguin.de .

My only guess is that something in the synchronization mechanism between GL clients and the graphics hardware has broken over the Xorg 7.0 update. Is this at all possible? Does anyone have a clue as to what's going on?