It depends wildly on the type of game.

e.g. if you're playing a single player turn-based strategy game, you might be taking a few seconds between each decision & UI interaction. Some hard turns you might step away from the computer to think things through for minutes without touching the controls. 30fps for a game like that could be fine. 15-20fps might even be fine, especially if the game engine manages to avoid adding unnecessary input latency & is able to process input events at a faster rate even if the render runs at a low framerate.

If you're playing competitive FPS games, where reflexes matter, you'd want to get input, network & video latency as low as possible, within reason. Not high-frequency trading low. I have no idea at what point it stops making a competitive difference. If you have +100ms more latency than I do, I suspect that'd give me a noticeable advantage. If you have +10ms more latency than I do, I'm not sure that matters.

Dan Luu wrote an article about input latency [1] in 2017 where he measured latency by running experiments pressing a key & measuring how long it takes to see a response on the screen. New computers from 2017 would have around 70ms-170ms latency, depending on the model.

[1] https://danluu.com/input-lag/

I very much don't trust that article as a baseline. YMMV but I measured with a 240hz camera with a mid-high tier computer and a 144hz monitor in 2018 and a nice computer w/ 165hz in 2025 and I never got the huge latencies he experienced, I had click to photon of something like 10 frames max, so 42ms, with the average IIRC being closer to 5 frames.

input lag is a minor part of it. it depends on the game, but for example in CS2, refresh rate changes game mechanics like recoil, movement, even trajectories of thrown grenades.

i went from 60hz to 240hz, with <100fps average, and the difference was still immense. refresh rate is more important than fps, that's how big it is.