Long story short though, the Linux 3.11 performance for the Nouveau kernel driver isn't too exciting. This reverse-engineered open-source NVIDIA Linux graphics driver is excited in Linux 3.11 for the VP2 H.264/MPEG-2 video acceleration support, but when it comes to OpenGL performance, there doesn't appear to be any fundamental breakthroughs.
The Nouveau DRM in Linux 3.11 doesn't have any notable improvements when it comes to re-clocking for maximizing the performance of NVIDIA graphics cards. There also isn't anything else crazy aside from the Nouveau video acceleration, which is great for HTPC users.
On the user-space side, Nouveau Mesa 9.2 benchmarks showed the Nouveau Gallium3D drivers having no major performance breakthroughs in the upcoming Mesa 9.2 release either. For these re-clocked NVIDIA GeForce 9800GTX and GeForce GT 220 graphics cards, the Linux 3.10 and Linux 3.11 Git kernels (as of 6 August) were compared on the same Intel Core i7 4770K Linux system.
The benchmark results in full can be found via OpenBenchmarking.org within 1308072-SO-LINUX311N99, but long story short there's no major changes to find with the upcoming Linux 3.11 kernel release.