Okay, I sideloaded a customized mobi book to the Kindle library on my iPhone 6+. I can confirm that the book does not refresh when opened nor does the app refresh when I open it with that sideloaded book open. So I guess it is only the Amazon books that were directly downloaded that refresh. I'm guessing that the Amazon books have so many bells and whistles now what with Xray, and all the other junk I rarely use or want, that they have become bloated. My iPhone is fast enough that I don't see any slow down in page turning or other functions though. And no, I never noticed my Kindle Voyage doing the refresh thing like the iOS app is doing.