I was debugging gnome shell slow performance on openSUSE 13.1 when I noticed in libgl verbose output it was failing to load my drm drivers with the error failed to open drm device Permission denied. Adding myself to the video group fixed this error and seems to have made Gnome Shell run faster.
I think disabling the video group by default was a mistake. I believe I read in the past it broke Nvidia proprietary drivers also.
Does anyone else have this issue? I found it by running:
LIBGL_DEBUG=verbose gnome-shell --replace &
I am using an intel gm45.