So a while ago, i asked a question about how I could possibly improve my TF2 gaming experience on a HP Pavilion dv6000. I average 9 FPS. As the dv6000 doesn't really have a graphics card (that integrated piece of $#!+ doesn't really count, its so bad), I've looked around, and found that lowering my directx levels will almost double my FPS. So I've lowered it to directx 8.1 and i dno't see any problems except for the spy not showing what its currently disguised as on my screen, but i can live with that
my question is why does lowering DirectX level improve gaming performance?