But it'll lag on Duel Core (and Below) processors if you are doing other stuff at the same time (eg. Saving/Moving big files).
Still, there's no reason why the option would not be implemented.
@gamer: The GPU (or graphics proccessing unit) is built onto your graphics chip so that programs can use it to calculate rendering effects, such as lighting. Therefore its smart to put it on the GPU rather than CPU.
Featherweight bricks run on GPU (if your computer can handle it/has to be brand new since both of my strong computers don't have it), so this will too.