When is good enough to the point of speed? Things are often down to your users perception, right? You don't necessarily need to continue making something faster from 100 milliseconds to one millisecond if it's some sort of UI interaction. So there's heuristics, if you will, that can kind of help guide where you should shoot for. But at least in the web world, maybe even in apps for APIs and stuff, there's a lot of stuff that doesn't go much faster than about 100 milliseconds.