Maybe a stupid question and maybe I'm not understanding vsync but I thought that vsync only reduced the FPS of a game when the monitor's refresh rate couldn't keep up with the fps.
By this logic, if the monitor's refresh rate is constantly higher that the game's FPS, vsync should not do anything?
My monitor is 240hz and my game runs at 200FPS max. I have vsync on and it's costing me lots of performance (if I disable vsync, the game runs at 400FPS). In this case, what is vsync doing exactly that is so expensive? Should it not be dormant when there is no FPS to reduce?