Intel Graphics: Windows 7 & Windows 8 vs. Ubuntu 13.04 & Fedora 18
The more recent OpenArena release (v0.8.8) makes use of GLSL and other more recent OpenGL functionality compared to OpenArena 0.8.5. With this OpenArena release, it's one of the only OpenGL benchmarks where Ubuntu and Fedora Linux are running ahead of Windows 7 and Windows 8.
For the Qfusion-based Warsow, Windows 7 SP1 was running faster than Windows 8 on this Intel Core i3 system with HD 4000 Ivy Bridge graphics. Both releases though were faster than the latest releases of Ubuntu and Fedora.