I saw your post with the link later and I've now read that post. The one thing that might be killing me is "News" which is new and it was enabled in the Enable Background App Refresh. I had not heard of the Background App Refresh option before. I've turned most (all?) of those off now. Thank you for the pointer to the article.
It is sad because the one app I would like is to have Mail check for mail every 15 minutes or so even if it is not in the foreground but I'm not sure if it can do that. Its not listed in the Background App Refresh list. My imap servers (as far as I know) can't do push notifications.
Off topic slightly but I've also found how to delete apps from iTunes this morning and I'm doing a lot of house cleaning right now.
The pipe coming into my house is soooooo small that I really have to manage the network activity. Even where I work, the pipe may be big but there are so many other people using it that the download speeds are often slower there than when I'm at home.
I'm turning off the automatic updates from the app store, etc. What I plan to do is update the apps on iTunes and then push them to my various iOS devices so I only download them once. ... I'll see how that works.
But... back on topic: I don't know why, but since the iOS 9 update my iPhone 6+ is struggling and I'm believe it is due to network bottlenecks rather than CPU. I see where we can monitor battery usage but I'm much more focused on network consumed. My battery life for my iPhone isn't a problem for me at all. With my iPad its been a slight problem just because I often read a book on it for most of the day and then forget to plug it in at night to recharge.