Radeon: Mesa 10.1 vs. Mesa Git On Ubuntu 14.04
Running OpenArena didn't reveal much of a performance change for the four tested AMD GPUs on the R600 and RadeonSI Gallium3D drivers when comparing Mesa 10.1.0 devel to its Git point just past the Mesa 10.2 branching.
The id Tech 4 Prey game also revealed no performance differences out of the newer Mesa stack.
There also isn't much to see with the Unigine Sanctuary results for this latest Mesa graphics driver code.