My 2c:
for quick rendering of pdf documents on evince, especially those containing plenty of images, or (horror!) those made of scanned book pages without ocr'ing into text, I convert to djvu format using the --monochrome --lossy parameters. Evince reads djvu quite well and quickly.

For writing essays: use notecase. Write your paper as a collection of several notes, which you can navigate quickly on your tablet, and then export as a single formatted document when you're done.