Originally Posted by
Merenor Settings>Privacy>Background apps
Yep, or just type "back" into the first Settings screen, in the search box, and it's the first one in the list.
This shouldn't affect your reading an e-book, at all, but there's probably an app that's a lot more efficient, for doing this, such as Amazon Kindle, or similar...
Reading it in a browser will likely cause periodic refreshes and such. A reader-app will try to minimize this, for power, by pre-loading a few pages on either side of your current "bookmark", and only load new sets of pages when you flip past a certain threshold.