I have problems with some of my books on Ipad.
With most of my books it works all right. But some books are incredibly slow. It may take up to 1 minute to turn a page (sometimes even longer) - and sometimes the app just crashes and then it takes several minutes to open the app again.
I have downloaded about 50 books. Some books that made the app crash and be very slow are John Owen's Hebrews commentary and some journals. This happens even though I put the Ipad in airplane-mode.
Today I gave up on reading Journal for Biblical Manhood and Womanhood as the app was several minutes about turning a page and finally crashed.
I tried reading another book and there was no problem: Quick turning of pages and no crash.