Hi, I'm on Mac and got this problem since the very beginning. After a loading screen a frame-rate may or may not drop - it look random for me. It's extremely annoying but you don't have to restart the game. Just go to graphics options and check/uncheck Vsync (it depends on what you currently got), save the settings and go back to the game. Now the frame-rate is normal The problem is I got to do it every 5-10 minutes so I really hope (expect?) to see it fixed in the next patch.