Slow on iOS

Im a nursing student and we are automatically charged for our e-books, which we must view using vital source. This app is so slow its frustrating. It takes at least 10 seconds at times to just highlight or delete/change a highlight. Scrolling is also slow at times. I dont get why an app that takes up so much space can be this slow. Im very annoyed with this app.

ARLopez85 about Bookshelf