I prefer to PR e-books instead of printed text and I use the auto flip option in Adobe (i.e. I don't turn the pages by clicking 'Next Page' , instead the pages turn automatically).
My auto flip speed is 0.01 second, thus I finish PR-ing a 400 pgs. book in 4 seconds. Is that too fast? Will my subconscious be able to absorb all the info in the book at this speed (100 pgs./sec)? What is the maximum speed in the photoreading step?