Lastly, when running the "Nexuiz successor" at 2560 x 1600 with the three visual quality settings, Ubuntu 12.10 continued to lead when using the KDE desktop -- this was now even the case for the affordable GeForce GT 220 graphics card.
It depends upon the actual OpenGL application/game, but overall the NVIDIA binary graphics driver that is comprised of largely common code across supported platforms (Windows, Linux, BSD, and Solaris) can perform at the same speed between operating systems. However, with the dual testing of Ubuntu (Unity) and Kubuntu (KDE), there are certainly bigger areas that can impact the overall OpenGL performance of your GeForce system. Hopefully by the Ubuntu 12.10 release in October, more of the Unity and Compiz performance issues will be fixed since it's the default desktop for the popular Linux distribution and what most people use, which right now is hampering the Linux performance battle against Microsoft Windows.
If on Ubuntu you happen to be using the open-source Nouveau driver for the NVIDIA graphics support rather than tainting your kernel with this binary blob, unfortunately, those numbers are rather troubling still and will be the focus of a future Phoronix article with the forthcoming Mesa 9.0 release, etc.