>If you are in the middle of typing a comment and switch to another app, when you come back, it will reload the display, losing your comment.

This is the rule for a lot of apps and mobile websites now. I don't understand why - we have so much RAM available - but they love to refresh whether there's a reason to or not. And even if there's a reason not to. I can't count the number of times I've tapped on a tab that has a minature version of all the information I want, only for it to be replaced by a loading screen or 404.

A while ago I noticed my battery usage had gone way up. It was because any time I was distracted from my phone (or lost internet connection on a train), I would just leave the display on. Locking the phone meant that I'd lose whatever context I had.