You start to read. Especially if some of the books contain hundreds of pages. Develop the skill of speed reading onscreen. Lighting should not produce glare. Poor lighting can greatly reduce reading speed.
High contrast is preferred on the screen so the print has the greatest clarity.
This also improves comprehension. Use speed reading techniques. Use one hand to hit the 'Page Down' key and the other hand to hold and operate a guide such as a ruler. Holding the guide an inch or so away from the screen, move it down at a reasonable rate, or use sweeping motions across the screen. This encourages the eyes to take in larger sections at a time, especially making use of peripheral vision.