This is pretty much true for every game. Especially game with lots of foliage. Take Lineage 2 for example. Back when it was newer, when I had Shadows on it would kill my performance, but turning JUST Shadows off, everything else can be at max and my computer was completely fine. It seems to be that way for every game. Whenever I have issues with performance, the first thing I do is remove shadows, and it usually nearly doubles the FPS.
