it tries to prevent sudden quick fps drops. Unreal engine locks it to whatever the application thinks your computer can handle. If your max FPS is 120 with dips of 40 then it’s going to set it at its smoothest framerate (hence the name). So it will set it at a maximum of 60fps with a minimum of 40. What’s the point of this, you might ask. It’s to prevent stutters that would normally occur with vsync and no vsync.