Why does Subby need to be fast? Just get good with Ice Clone, Ice Puddle, and Ice hadouken, and you have all the time in the world to combo them into oblivion.
All I'm hearing is "Why isn't Sub Zero perfect at everything forever!"
My one friend who usually hates MK games picked up Sub Zero and started doing fine with him. He didn't have any preconcieved notions about how fast he aught to be, and he liked him a lot. His one complaint was that he doesn't have a lot of moves compared to other characters.