Composite of advice from several  saints:

Read slowly, with attention & recollection; stopping to consider,  ruminate and think about the truths that affect you most intimately.

Calmly, apply your intelligence to understanding. When a passage is particularly moving, pause to consider it more deeply with the Lord.

Life is too short. Be content with re-reading books that lead you closer to God and do not waste your time on worthless and unprofitable selections.