'typical' might be a bit of a stretch here: I doubt that without tuning settings on a standard OS like Ubuntu/Windows and with your typical 60 or 75Hz monitor it's possible to achieve numbers this low (I've measured software->monitor latencies, good luck getting lower than 2 frames, and that's excluding input and processing). Anyway since this is largely theoretical, what would be really interesting here to actually measure this with external hardware and see what the actual numbers are. Think 2-channel oscilloscope, channel 1 probing keyboard key activation and channel 2 measuring a photovoltaic sensor taped to the screen. Anyone did that already?