This is designed to work with all games so it’s more similar to how many emulators implement quick save than how it works in most games. I suspect or rather hope that it’s as fast (instantaneous) as it is in emulators.

It also appears that it’s supposed to rewind like you can do in some racing games.

It’s more complicated than a simple quick save button found in mostly older games. It’s a neat feature but I would obviously prefer that they didn’t get the patent so Xbox also could implement something similar.