Try installing the Calibre KoboTouchExtended plugin, and send a book to your Aura via USB. That should convert it to Kepub, and will greatly improve the responsiveness.
I have a post with more details, (including tweaks to make full screen reading work, as an alternative to firmware patching, if you like.)
https://www.mobileread.com/forums/sh...&postcount=336
but installing the Calibre driver and loading a book is all you need to do to see for yourself if the speed is more to your liking.
Based on your description of frustration, however, I have to wonder if you're trying to read a pdf or comic (excuse me: graphic novel/manga) book?