For this posting are simply some benchmarks on Mesa 9.2-devel (9.2 Git branch) vs. Mesa 9.3-devel (Git master) as of 15 August when using Intel Haswell graphics in the form of HD Graphics 4600 on a Core i7 4770K CPU. The benchmarks were mostly driven out of curiosity sake and in further testing the ECS Z87H3-A2X Extreme motherboard.
There have been some Mesa performance optimization commits since the Mesa 9.2 branching, so it will be interesting to see if they have any impact on today's test results. This straightforward comparison done atop Xubuntu Linux can be found at 1308151-SO-MESA93INT90.
Hit up the link for details in full, but long story short is that there isn't too much to see right now for Intel Haswell on Git master when it comes to performance. Of course, we'll keep monitoring the changes and let everyone know when we've spotted some worthwhile commits.