When running Xonotic at 1920 x 1080, KDE was back to performing significantly faster than using the default Ubuntu desktop. However, the Intel Windows driver continued to be much faster for Sandy Bridge and Ivy Bridge with all tested image quality settings.
To no real surprise, the Intel Linux OpenGL performance is still sub-par compared to the Intel Windows driver. The Intel Windows driver is in better shape but at least the Intel OTC developers have been making great progress in recent years in terms of slowly but surely catching up on OpenGL compliance, display and 3D features, and more timely hardware support. Intel is planning more OpenGL Linux performance improvements going into next year. Haswell and Valley View Linux preparations are also well underway.