With the OpenArena games, the Intel Ivy Bridge performance on the ILO Gallium3D driver isn't too far behind the official Mesa graphics driver. However, as many Phoronix readers know, this open-source first person shooter isn't very demanding on modern GPUs and drivers.
While Reaction Quake 3 is still based upon the ioquake3 like OpenArena, it's much more demanding on hardware. For this game we see the ILO Gallium3D driver running at less than a third the speed of the official Mesa (non-Gallium3D) open-source GPU driver.