Share your experience!
You probably have other apps/services running in the background, creating this issue, what you can do is test it in >>> safe mode for a couple of hours or repair the phone with XC
Alternatives on How to backup Xperias
what are the top 6 items on that list ?
I have quite the same issue on my z5, since around two weeks it's crashing especially when starting Apps, e.g. Spotify... Sometimes it just takes very long (around one minute) until something happens and sometimes it directly crashes. And today while listening to music, i noticed the heat issue, normally the phone just gets warm while playing games, but today it got really hot and I wasn't even really using it. Tried already the Sony repair Software but didn't help either.
You should test the phone in safe mode most likely you have a lot of background apps running.