Input lag
What input lag is, what causes it, and the settings that reduce it most.
Input lag is the delay between pressing a button and seeing the result on screen. It is measured in milliseconds, and while it sounds like a small thing, it is what makes a game feel responsive or sluggish.
Rough guidance: under 15ms is very good, 15 to 30ms is fine for most players, above 40ms starts to feel noticeably delayed in fast games, and above 80ms is a problem even in slow ones.
Where the delay comes from
It accumulates across the chain. The controller sends the input; the console processes it and renders the frame; the display receives the signal, processes it and shows it. Each stage adds a little.
The largest and most fixable part is almost always the display. A television doing motion smoothing, noise reduction and various picture enhancements can add 80 to 120ms on its own — far more than everything else combined.
How do I reduce input lag?
Turn on Game Mode. This is the single biggest improvement available, and it is free. Game Mode disables the TV''s post-processing. The same television can go from around 100ms to under 20ms with this one setting.
Turn off motion smoothing — TruMotion, Motionflow, Auto Motion Plus and similar. It is a major contributor and Game Mode does not always disable it fully.
Raise the frame rate. A game at 60 frames has roughly half the frame-related delay of one at 30. Choosing Performance mode over Quality mode improves responsiveness as well as smoothness.
Use a wired controller for competitive play. Wireless adds a small amount; it matters only at a high level, but it is real.
Enable ALLM if your TV supports it, so it switches to Game Mode automatically when the console starts.
Why it matters
People often blame a controller or their connection for a game feeling unresponsive when the actual cause is a television left in cinema mode. If a game feels heavy and you have not checked Game Mode, check that before anything else — it costs nothing and is usually the whole problem.