Our bodies have very fast nervous system. If I want to move my hand I can’t notice the delay between my decision and the actual start of the movement.
And we expect such fast reaction from our computers. After all they are our right hands:) Even small delay causes frustration… Of course longer delays are bigger disappointments but just 0.2s is easily noticeable. You maybe disagree about frustration but don’t forget that feeling is accumulating over the time.
Actually 0.2s delay is really not bad for computers. Some systems are considered healthy even with responses 10s long. A good programmer will notice right away what was screwed up.
I will bet that the main reason why the native apps are preferred over online apps is that lag in responses. In case of web browser many things happens on the way. In case of native app used GUI library can be to blame. But the biggest problem is the final code. Callbacks to user clicks and swipes. Having some kind of cache for user responses is really professional way to deal with it. But not always possible.
If you look at these Computer Latency Measurements you will notice that a newer computer doesn’t mean faster responses. Newer hardware uses newer and more complicated OS. I have feeling that engineers balance on that edge of noticeable delays. Balancing is OK … until you fall.