I have a problem with my game. When the frame rate is under fps_max some entities start to "vibrate". For example if I have fps_max=60 and a frame rate of 60 all runs perfect and smooth, but when the frame rate fall for example to 40 then some moving entities start to "vibrate", but if now I set fps_max=30 I get a frame rate of 30 and all runs smooth again. Anyone knows how i can fix this?