WARNING: Some bad words might be used in the following post. Don't say I didn't warn you!
Another good example is The Two Towers from Tolkien's Lord Of The Rings trilogy. The first time I read it, back in high school, I think I read it in three, four days. Now however, I've been stuck at Frodo and Sam's journey for weeks. It is possible this is because I am so used to reading fast paced books, that that second part of the book is too slow for me right now.