From an Intel Core i5 6600K system I conducted some benchmarks of Mesa 11.0.2 as available by default on Ubuntu 15.10 compared to Mesa 11.2-devel when enabling the Padoka PPA on the same installation with the exact same hardware.
Linux 4.5 was in use on this Ubuntu 15.10 installation, aside from that it's a rather stock Ubuntu 15.10 environment.
In some tests, the performance is actually lower.
However, in other tests the performance has certainly improved.
Team Fortress 2 is running slightly lower on this Intel Skylake setup with HD Graphics 530.
To see more of these benchmark results of Ubuntu 15.10 with Mesa 11.0 vs. Mesa 11.2-devel Git from a PPA, see this OpenBenchmarking.org result file. Of course, consider upgrading on your own and be forewarned about possible regressions and other problems from running the Git code of open-source Linux graphics drivers.