Comment 1 for bug 1566157

Ah, I forgot to include the results without a window manager as a comparison:

$ killall metacity & sleep 5 && glxgears -fullscreen & sleep 20 && killall glxgears
44884 frames in 5.0 seconds = 8976.656 FPS
44905 frames in 5.0 seconds = 8980.993 FPS

Normalized: 118 FPS, the fastest of all.

$ killall metacity & sleep 5 && glxgears -fullscreen & sleep 20 && killall glxgears
1743 frames in 5.0 seconds = 348.422 FPS
1713 frames in 5.0 seconds = 342.471 FPS

Normalized: 94 FPS, slower than compiz. That may be due to compiz not using the whole screen in glxgears -fullscreen; the drawing area didn't include the panels.