So instead of getting 10 frames per second, we will get 15 frames per second.
MASSIVE
Also, it's being optimized by incompetent people. You know, the same guys that said 1.4 will bring "significant performance increase for gamers with SLI / Crossfire".
We all know how it turned out. FOUR months later, I still can't use my second GPU.
That's how good they are at "fixing" the engine.