Rotating Sprites in C

I've spent the last few weeks trying to optimize my game as it's become almost unplayable in it's current state. I've found that the biggest drain on time is that every bad guy and good guy has a repeating scheduled function that rotates it toward the direction it's moving. I have feeling that this exactly that sort of thing that I should be doing in the engine. I've never really touched the engine yet, so does anyone who has know if this sort of thing would be possible?

-Peter