Your doing well. It gets even better with practice.
If the book had 36000 words it would take the average reader at 200 wpm at least 3 hours to regular read. (200 page books usually have 50,000+ words so would take even longer really more like 4.5 hours)
At first your activations may seem take a little long. Try setting a timer for 30 minute session. what you didn't get the first 30 minutes you give yourself another 30 till you feel you got it/ or had enough of it.
You're on the right track... keep up the good work, if you keep practicing can you image how much better you'll get - wow 
Alex
