> as an emulator author, you get people presenting new zany latency reduction ideas that defy the laws of physics all the time, and they completely dismiss your own experience in the field, and it's like kids constantly saying, "are we there yet?" on a long car ride.

Yep, that seems to be the usual for nearly every emulator scene.

> But it's probably possible to isolate similar test cases for each source of latency. In a lot of cases (kernel audio mixing, keyboard responses), we're probably talking much smaller latencies than CRT vs LCD monitors, so you'd need a huge amount of precision.

I was thinking of a test program that inverts/cycles the screen colour on registering a keypress. Put a photodiode in front of the monitor and use an electrical switch across the controller button contacts. Cheap parts and an oscilloscope will give microsecond resolution for the end-to-end net case. Unfortunately not everyone has this kind of setup lying around.

I seem to remember someone marketing a commercial device that did something like this for timing CRTs vs LCDs but can't remember the name of it.