Depends on the game and video card, on the 3rd birthday it gives a speed up last time I checked, since it dynamically builds shaders it could overload the video card driver so unless you have a really good video card that can handle lots of shaders it will probably be worse performance, and possibly some graphical glitches.
304.48 is virtually the same driver but with working shaders, it's up to you if you want to downgrade
304.48 is virtually the same driver but with working shaders, it's up to you if you want to downgrade