Phoronix published a review on the Mesa 9.2 Can Boost Intel Haswell Graphics 30~40% On Linux
A quote from the article:
Yesterday I shared open-source Linux graphics benchmarks showing the Intel Ivy Bridge performance improving on Mesa 9.2 over the earlier releases of this important open-source Linux graphics driver component. However, for the latest-generation Intel "Haswell" graphics, Mesa 9.2 is an even more important upgrade. Here's a look at the performance benefits in moving from Mesa 9.1 to the soon-to-be-released Mesa 9.2.Mesa 9.2 Can Boost Intel Haswell Graphics 30~40% On Linux @ Phoronix
With Intel Haswell processors only having been released in early June and Mesa 9.1 being from early 2013, there's been months worth of performance optimizations building up for Haswell that aren't yet found widespread on the Linux desktop for owners of the new CPUs. (Fortunately this will be improved in the future with a new Mesa release process.) Ivy Bridge performance also improved as the aforelinked article shows, but Haswell is quite noticeable as the Linux support is still stabilizing, becoming feature-complete, and catching up to the Intel Windows driver. (The long-awaited Intel Haswell Linux vs. Windows results are also forthcoming, but the latest delay is due to having to order a new Microsoft Windows disc after losing the previous one, but that should be here in the next day or two.)