Weird stutter/hitch occurs randomly.

[miaou_ml]

Having the same issue and I've tried so much to fix it. I'm able to get 80+FPS normally but the stutter will send it down to 20FPS for 1 second. Often it will cycle back and forth between 60 and 20 for a few seconds before going back up to 80.
It most definitely has nothing to do with the driver because none of my other, more graphically intensive games are behaving this way. FFXIV itself is just not cooperating at all with the GPU's vsync and frame creation.