Speed-reading gets you to the last page. Slow reading gets the last page into you.

Finishing and absorbing are two different accomplishments, and only one of them is easy to measure. Racing through leaves you with a page count and a vague impression, which is why you can read something and remember almost none of it a week later. The slowness is not wasted. It is the part where the thing actually goes in.

Take one chapter this week and read it at half your usual pace, stopping when a sentence does something to you. Put the book down and say the idea back in your own words. Getting through less and keeping it is not a worse trade.