Comment # 2 on bug 65192 from Michel Dänzer

(In reply to comment #2)
> Setting R600_HYPERZ=0 in /etc/environment didn't help.

Are you sure this ended up in the environment of the screensaver hacks? Can you
try e.g.

R600_HYPERZ=0 /usr/lib/xscreensaver/antmaze

manually to see if that works better? Same thing might be interesting for
R600_DEBUG=sb (or R600_LLVM=0, but AFAICT you're building without the r600g
LLVM compiler backend anyway?).