Xonotic with low quality settings at the 1920 x 1080 HD resolution was also in favor of Windows 7 for both the Intel "Gen6" and "Gen7" graphics. Windows 7 OpenGL with the i5-2500K was 81% faster than Ubuntu 12.04 with the updated graphics stack while the Ivy Bridge processor was also about 80% faster under Windows.
When upping the image quality to high, Windows 7 was still faster with the Intel HD 3000 graphics by 77% and the Intel HD 4000 graphics under Windows was faster by 52%.
Lastly, the Xonotic effects quality was set to ultra. With the ultra image quality affects, Sandy Bridge on Windows 7 was still 21% faster and Ivy Bridge was separated by about the same margin.