Phoronix published a story that the Intel Linux OpenGL drivers is still slower then it's Windows counterpart

Recently there was the NVIDIA graphics comparison under Windows 7 and Linux providing new data at how the cross-platform NVIDIA driver is comparing between Ubuntu 12.10, Kubuntu 12.10, and Windows 7 Pro. Aside from Ubuntu's Unity desktop with Compiz impairing the performance, the results were competitive. Next up now is a look at Intel Sandy Bridge and Intel Ivy Bridge graphics when comparing the performance of the three operating systems.

This modern look at the Intel Linux versus Intel Windows drivers was done from an Intel Core i5 2500K "Sandy Bridge" with HD 3000 graphics and then an Intel Core i7 2700K "Ivy Bridge" with HD 4000 graphics. The rest of the system remained the same during the testing on all three OS configurations. Microsoft Windows 7 Professional with all service packs / updates were used as of this month and with the Intel 15.26.12.64.2761 graphics driver. On the Linux side an Ubuntu 12.10 development snapshot was used while pulling in the latest Linux 3.6 Git kernel, libdrm, xf86-video-intel DDX, and Mesa 9.0-devel as of test time. Between the Ubuntu and Kubuntu results the only effective difference is using KDE 4.9.0 rather than Unity 6.4.0 with Compiz.

  Intel Linux OpenGL Driver Remains Slower Than Windows