What does VSync do in games?

Vsync in Games

Vsync, or Vertical Sync, is a graphics technology that synchronizes the frame rate of a game and the refresh rate of a monitor. By synchronizing these rates, Vsync eliminates screen tearing, a visual artifact that occurs when multiple frames are shown in a single screen draw. In essence, it helps to ensure smoother gameplay and visual stability.

Effect of Vsync on FPS

While Vsync provides smoother gameplay, it tends to limit the framerate to the monitor's refresh rate, usually 60Hz (60 FPS). This means if your game can originally run above that rate, enabling Vsync might cost you FPS. The decline in FPS could be more noticeable if the game's frame rates fluctuate a lot — because Vsync can only cap to integer dividends of the monitor's refresh rate (like 30 FPS, 15 FPS), it can drop the frame rate lower to match the nearest level, leading to perceived significant performance drop.