Early this morning I published some new Nouveau benchmarks from Mesa 9.2-devel. After that testing, from the Lenovo ThinkPad W510 with NVIDIA Quadro FX 880M graphics, I then compared recent Linux kernel releases. The Linux 3.9 Git kernel as of yesterday was compared to the vanilla mainline releases of Linux 3.8, 3.7, and 3.6.
While there isn't any breakthrough performance gains to find with Nouveau on Linux 3.9, at least for this particular hardware, there are some modest improvements over recent Linux kernel releases. For those unfamiliar with the actual Nouveau DRM driver changes in Linux 3.9, see The DRM Pull Request For Linux 3.9. The Nouveau changes this time around though aren't particularly thrilling.
All benchmarking was handled in a fully automated and reproducible way using the Phoronix Test Suite open-source software. All of these benchmark results in full can be found on OpenBenchmarking.org within 1304103-FO-NOUVEAULI32.
For some tests, the NVIDIA Quadro FX graphics performance on this reverse-engineered driver edge slightly higher with Linux 3.9 over 3.8/3.7/3.6.
World of Padman delivered the biggest performance jump with Linux 3.9.
There are more OpenGL Nouveau results on OpenBenchmarking.org. The good news is that while the gains weren't always very noticeable, there doesn't appear to be any serious regressions, at least for this "GT216GLM" graphics core. More Nouveau benchmarks of Linux 3.9 are coming, including a big Nouveau vs. NVIDIA Linux comparison.