Comment 93 for bug 252094

To clarify the situation a bit I made the following tests:

With no compiz activated:

$ glxinfo | grep direct
direct rendering: Yes

$ sudo glxinfo | grep direct
direct rendering: Yes

$ glxgears
2844 frames in 5.0 seconds = 568.693 FPS
2986 frames in 5.0 seconds = 597.155 FPS
2900 frames in 5.0 seconds = 579.849 FPS

$ sudo glxgears
2736 frames in 5.0 seconds = 547.065 FPS
3057 frames in 5.0 seconds = 611.340 FPS
3069 frames in 5.0 seconds = 613.760 FPS

With compiz activated:

$ glxinfo | grep direct
direct rendering: Yes

$ sudo glxinfo | grep direct
direct rendering: Yes

$ glxgears
2946 frames in 5.0 seconds = 589.101 FPS
2995 frames in 5.0 seconds = 598.924 FPS
3015 frames in 5.0 seconds = 602.967 FPS

$ sudo glxgears
2930 frames in 5.0 seconds = 585.985 FPS
2676 frames in 5.0 seconds = 535.103 FPS
2656 frames in 5.0 seconds = 531.038 FPS

My conclusions:

1. If your direct rendering as a user is not working according to glxinfo check if it works with compiz disabled. And vice versa.

2. There is no significant difference in performance when run with user previliges or root previliges.