Onyx BOOX. Set the refresh rate to anything faster than "Normal"/"Regal", and you can page through docs pretty much as fast as you'd care to.
NeoReader (Onyx's book reader app) also has a lightbox / page preview mode where you can see 4, 9, or 16 pages at once. Obviously too small to read at 16 pages up, but good enough to spot figures, diagrams, chapter breaks, and the like. That renders pretty quickly on ePub or generated PDFs, but can be slow on scanned-in books where you're looking at images of text rather than rendered text.
NeoReader (Onyx's book reader app) also has a lightbox / page preview mode where you can see 4, 9, or 16 pages at once. Obviously too small to read at 16 pages up, but good enough to spot figures, diagrams, chapter breaks, and the like. That renders pretty quickly on ePub or generated PDFs, but can be slow on scanned-in books where you're looking at images of text rather than rendered text.