As a Gnome user, I've been using Evince for a long time. Yesterday, tried to open a 30mb 20-page file, and it crawled. The pages would get rendered very slow and rerender on scroll.
I typed "fast linux pdf viewer" into a search engine and quickly landed at Okular, which has a setting to prerender everything and keep it in memory. It flies!
MuPDF is by far the fastest, much faster than Okular or Evince, both at rendering pages and at navigation through the document (also the keyboard-shortcut-based user interface of MuPDF is much faster than the more typical GUI of the other PDF readers).
MuPDF has various limitations and sometimes I find certain PDF files that it cannot render, so it cannot be used as the only PDF viewer.
Nevertheless, using MuPDF to handle the common cases of quickly opening, searching and reading PDF files, together with a fall-back more complete PDF reader, e.g. Okular, seems the best option on Linux.
Wow. It was in my repositories, has no silly interface buttons, and has a very short and useful man page. And indeed it's fast. I'm sold!
Now, I'd like to see double (facing) pages. And it seems MuPDF can't do that. So I'm stuck with Okular, which is sad, as it's the only reason for me to have QT installed...
I typed "fast linux pdf viewer" into a search engine and quickly landed at Okular, which has a setting to prerender everything and keep it in memory. It flies!