I am playing on WIndows 8. I have quite a few graphics mods, generally textures, but I tried getting rid of them and it didn't work. This was happening before so I tried a re installation, which seemed to change the areas where this happens. I will get varying frame rate drops looking at random things (eg. a random rock somewhere). I get very annoying, especially when the enemies are in the direction of the 'demanding area'. Does anyone have any idea what could be causing this?

Try lowering your graphics. if the mods aren't coming out i recomend u save urself the trouble and do a clean reinstall.

I have already tried reinstalling and lowering graphics