Comment # 7 on bug 103968 from Michel Dänzer

(In reply to Odo Wolbers from comment #6)
> Under /usr/local I found quite some files which look related to GL with a
> date of the last tweakings (22.Nov). Does it make sense to just delete
> everything from this date?

Yes, try that. If it doesn't help, provide the output of

 LIBGL_DEBUG=verbose glxinfo | grep ' render'