Firstly they can handle maybe more than many people think (8K or more depending upon the resolution available to scan).

Also - animated works perfectly - I actually have utilised an old "book reader" (with no internet capability or changeable OS) as a way of transferring multiple GPG encrypted private keys from an offline PC to an online one (I do this using its "slideshow" mode for displaying pics achieving around 8K per second - not very fast but that's the fastest it allows a slideshow to work).