Is 0.3 GHz less than System Requirements for a video game bad

It really depends completely on how powerful of a processor you have. A low-clocked mobile i7 might have an insufficient clock speed for a particular video game, but it will still shred said game in every manner possible.

In the same sense, a P4 can be 1GHz above the suggest clock speed, and still utterly fail to provide enough compute power to make the game playable.

Newer games rely on your graphics card more than your processor-- This is also important to keep in mind. If the game runs well, the MHz / GHz requirement for the processor is moot.