Stuttering/Random FPS drop on older expansions

Figured I would post in here because there's no other resource in trying to figure out the issue to this problem than what I've tried.

I've started with a fresh download of WOTLK and the game runs alright except for random instances I'll go from 60+FPS to 24FPS, or it'll just freeze for a minor second and restart. Along with this there's a small amount of screen tear.

I've tried VSync, full screen windowed, checked all my settings in NVidia, and everything else. This occurs on TBC also but not on Cata.

Anyone have any ideas on to fixing this?