You can Get drivers directly from NVIDIA, and sometimes they do offer a slight performance increase in games.
However they're horrible for everything else. I've had constant Graphics Kernel crashes in Screenflow, iMovie, FCPX, VLC, and other programs with it.
In games they're fine, but you need to reboot to swap between them. Personally I just use OS X drivers.
Personally I would just stick with OS X's drivers, and their updates, there seems to be a big one coming with 10.9.1 as the Seed has asked people to look at the Graphics, and Drivers specifically. Most likely gearing up for the new Mac Pro launch as well.