With laptops, there are really two limiting factors to performance:
1. The GPU. Laptop GPUs tend to be underpowered. In the worst case, you may be using an integrated intel GPU instead of a discrete GPU. Even at the high end, these are barely good enough for gaming.
2. Thermal profile. Laptop-class hardware is often unable to cool itself when running near capacity for sustained periods. This means that you might start off with reasonable performance but after a few seconds or minutes the performance may drop off (or worse, start to "pulse" between low and high performance).
Actual CPU speed is probably less relevant, except where thermal throttling becomes extreme. Certainly it won't prevent you from running the game, whereas having a below-spec GPU may.
chris
