Our latest Intel Linux graphics tests are of a Core i7 Haswell laptop with HD Graphics 4600 and testing the intel-drm-nightly kernel with the latest Intel DRM driver code being tested.
This easy weekend testing happened from the System76 Gazelle Professional laptop with an Intel Core i7 4900MQ CPU. The code being compared was the mainline Linux 3.10 stable and then the latest Linux 3.11 Git and drm-intel-nightly kernels from the Ubuntu mainline PPA as of 23 August.
If Intel Haswell owners were hoping for some performance improvements out of drm-intel-nightly, that sadly doesn't appear to be the case right now.
The straightforward benchmark results showing not much change over Linux 3.10 can be found on OpenBenchmarking.org within 1308242-SO-INTELDRMN58.