Guide
Input lag: what it is, how to measure it, and where to cut it
Input lag is the time from moving the mouse or pressing a key until the picture on the screen follows. High FPS helps, but it is not everything. Two games at the same FPS can have very different input lag, depending on how the frames reach the screen.
How frames reach the screen
Setting the game to Fullscreen fixes most of this. On Windows 11 Borderless can go straight to the screen too, but a window with borders always goes through the desktop.
- Independent Flip or Fullscreen Flip: straight to the screen, the least delay.
- Composed Flip: through the Windows desktop first, a bit more delay.
- Composed Copy: Windows copies every frame, the most delay.
Settings that add input lag
- V Sync holds FPS at the screen's rate and adds input lag. Turn it off in the game's settings.
- A window with borders costs FPS and adds input lag.
- VALORANT on NVIDIA with Reflex off. Set NVIDIA Reflex Low Latency to On + Boost.
- A graphics card at 100% all the time makes frames queue up. Lower the graphics a little, or cap FPS a bit under what the card can do.
- A mouse that reports unevenly because it goes through a hub or shares its USB port with something busy.
How to measure it
What a PC can measure is the time from the input a game took until that frame is on the screen. The mouse's own delay and the screen's are not in it. Move the mouse and press keys while it records, or there is nothing to measure. Measure in the same game at the same spot before and after a change, so you know which setting really helped.
Let Savenz Optimizer measure it
Result Card in Savenz Optimizer measures input lag together with FPS and the 1% low while you really play. It says how the frames reached the screen, straight or through the desktop, and keeps before and after in one picture. The Fixes page checks V Sync, window mode and Reflex in the games. For the mouse, see the guide on polling rate and USB ports. Questions? Ask in the Discord.