So let me get this straight...

You complaining that someone else got through a book at 2.5 hours? That isn't that long for some books so you don't know whether thats a long time.

You problem is that your not layering your activation. You need to pace your self. Your purpose can never be I want to get all the information in the book. You need to get trigger words and actively super read and dip. Rapid reading is optional and i know i can speak for myself when i say it is rarely needed. Try starting a mind map as early as you can and build it.
sorry if i forgot anything.

P.S. I know how you feel bout not getting replies quickly...