[CarVac]

There's a phenomenon known as Polling Drift where the 2x-per-frame input polling at 120 Hz is mismatched with the NTSC framerate that's 0.1% slower, leading to a variable 0-0.5 frame input lag. This can be patched out.

Additionally, they found that there is an extra frame of buffer hanging around that wasn't necessary so that can be removed.

There might be something else too?

[pezezin]

That sounds weird to me. Old game consoles with analog video output didn't generate perfect NTSC or PAL timings (for example, the Megadrive would actually run at 59.92274 Hz in NTSC, and 49.701459 Hz in PAL), but it didn't matter as the CRT TVs had some wiggle room and would synchronize to the video signal. There was no such thing as input and output running at different rates and desynchronizing.

[CarVac]

The problem isn't that the framerate isn't exactly the right frequency, it's that the controller polling frequency is not a whole multiple of the framerate.

The game uses the last poll, but the last poll could be up to half a frame old.

[robocat]

Another HN user mentioned a skipped frame every 20 seconds on a Dell monitor: https://news.ycombinator.com/item?id=32582085