Almost all of the rendering takes place on your CPU, on a single core of it. The only stat on a video card that "really" affects the game is the memory bandwidth, and that stopped to be a bottleneck somewhere around Geforce 7900 (or equivalent). Multicore support wouldn't be very helpful to this game, I think. Except the graphics, there isn't a lot of things that needs to be processed by the CPU in this game. Just getting the graphics over on the GPU would solve practically all performance issues.
However, making the game utilize a GPU properly is probably quite a bit of work, and that's why we probably won't see it happening.
