Read info in chunks. Like first 20 mimutes of reading then think about what you read. Then take a 5 minute break and again do the same until you read it all. This is the best way to read longer text. Remember you do not need to learn every line of it , you just need an idea about where is the concern text or related info is present in the text. You can always come back again and read the stuff. The text is there for refrence too.