Input Lag, FPS, and Hz - Rocket Science #3

Hey guys, welcome back to Rocket Science. In this Episode we're going to cover everything regarding input lag, FPS and monitor refreshrate. On the Rocket League subreddit I've seen alot of misinformation about input lag. Many claim that they have no input lag at all. While you may not notice any input lag, there is always some.

Input lag is the time delta between pressing a button and the action appearing on screen. There are a lot factors that play into how long this time is. First there is the input device. USB and wireless devices get polled a number of times a second and each time they report back which buttons are pressed etc.

Some devices poll at a rate of 100Hz which means it could take up to 10ms for the next poll to happen after you pressed the button. Wireless options may introduce a bit more input lag on top but that's hardly significant these days. Then the game has to process your keypresses and calulate what happens in the next frame.

This includes things like how far your car turns or the balls flight path. Once that data is available the graphics card can start working on actually rendering the image that is going to get displayed on your screen. At constant 60FPS this takes 17ms. Turning on vsync will add another whole frame of input lag and will also limit your FPS

to your monitors refreshrate. Once the frame is rendered it will be send to the monitor. How long it takes to transmit the whole image depends on your refresh rate. The monitor adds 2 extra layers of input lag. Pixel response time, which is given in the monitors specifications and Signal Processing which is usually the bigger factor.