I may have overlooked it, but i think it hasn't been mentioned those short freezes/hiccups are always occuring at the same locations, at least for me. For example if i walk down a certain hallway and there's this short hiccup, it will always happen RIGHT there.
I think those may be locations where parts of the map are loaded, or something to that effect. I have absolutely no other framerate issues, so i don't think it has anything to do with video settings.