alt Hacker NewsEvery single hardware subsystem adds lag. Double buffering adds a frame of lag; some do triple-buffering. USB adds ~8ms worse-case. LCD TVs add their own multi-frame lag-inducing processing, but even the ones that don't have to load the entire frame before any of it shows, which can be a substantial fraction of the time between frames.
Those old systems were "racing the beam", generating every pixel as it was being displayed. Minimum lag was microseconds. With LCDs you can't get under milliseconds. Luckily human visual perception isn't /that/ great so single-digit milliseconds could be as instantaneous, if you run at 100 Hz without double-buffering (is that even possible anymore!?) and use a low-latency keyboard (IIRC you can schedule more frequent USB frames at higher speeds) and only debounce on key release.
8khz polling rate mouse and keyboard, 240hz 4K monitor (with Oled to reduce smearing preferably, or it becomes very noticeable), 360hz 1440p, or 480hz 1080p, is current state of the art. You need a decent processor and GPU (especially the high refresh rate monitors as you’re pushing a huge amount data to your display, as only the newest GPUs support the newest display port standard) to run all this, but my Windows desktop is a joy to use because of all of this. Everything is super snappy. Alternatively, buying an iPad Pro is another excellent way to get very low latencies out of the box.
I really love this blog post from Dan Luu about latency. https://danluu.com/input-lag/