First up with Lightsmark, which is largely CPU bottlenecked with modern graphics hardware/drivers, the Windows 7 performance was much faster than Ubuntu Linux. Ubuntu 12.04 LTS with the latest driver at the time of testing was shy of 600 FPS where as Microsoft Windows 7 Professional x64 had no problems churning out more than 848 FPS.
While Ubuntu 12.04 LTS lost to Windows 7 with Lightsmark, when running the DarkPlaces-based game at 1920 x 1080 with HDR, the NVIDIA Linux graphics driver controlling the GTX 680 was faster by about 18%.
Unigine Heaven was slightly faster on Windows 7 than Ubuntu 12.04. At 1920 x 1080 this meant a 5% performance difference while at 2560 x 1600 it widened to 12%.