It's also different from game to game. I think in Witcher 2, for example, I had to set pre-rendered frames to 1, or else I would get horrible stuttering, even though the framerate was around 60. Or Call of Juarez: Bound in Blood, in which I always had very high FPS, but the game literally hurt my eyes. It felt somehow...jerky and not fluid. Unfortunately, I couldn't find a solution there.