If you have a simulation where realtime is 60 fps, you could simulate a little over 4.5 hours per second if you could run it at 1M fps. That would definitely help with learning rate.
He's not saying "break realtime into microsecond chunks."
He's saying: run through 4.5 hours of 16 millisecond chunks of time in a second. This is good for regression testing or producing training data quickly.