XMir Performance Measured On Ubuntu 13.10

The Qt4 performance with the X RENDER back-end took only a small performance hit with Mir in the stack.

When running full-screen OpenGL games on the System76 Galago UltraPro with Haswell "Iris Pro" graphics, the performance hit was very minor. It will be interesting to see how the Mir-native performance is once some games/benchmarks are ported over -- or in particular, a Mir back-end to SDL being added.