Assassin's Creed IV: Black Flag is a gorgeous game, but if you've played it on the PC, chances are you've noticed the erratic frame rate. Whenever the action kicks up, the frame rate drops, often precipitously. This is caused by V-Sync -- if V-Sync is active, the game will only run at either 60 or 30 FPS, and if it can't maintain 60, it'll...