Anyone know why Fraps would fix my microstutter?

I was having an issue where panning the mouse around in the evil within would cause everything to seem slightly choppy. yet, somehow, enabling fraps to check out my framerate keeps the game running at a solid 60 fps with no issue whatsoever...

i can't even begin to explain how this could be...

oh and getting even stranger, it ONLY works when i have the fps overlaid on the screen. when i have the counter hidden it goes back to choppy. no clue whats going on there