MuPDF is a Free and open source PDF and XPS viewer that focuses on speed, small code size, and high quality anti-aliased rendering. You can use MuPDF on a old machine to quickly open large PDF files.
MuPDF supports PDF 1.7 with transparency, encryption, hyperlinks, annotations, searching and more. It also reads OpenXPS documents. It does not support interactive features such as form filling and JavaScript.

Install MuPDF in Ubuntu

MuPDf is available in Ubuntu Software Center, just search for and install the mupdf package. It’s a little out of date. For the latest version, use the ppa:guilhem-fr/mupdf

Launch a terminal window from the dash home or press Ctrl+Alt+T. Copy and paste this command into terminal and hit enter to add the ppa:

sudo add-apt-repository ppa:guilhem-fr/mupdf

Then update your repository and install MuPDF

sudo apt-get update && sudo apt-get install mupdf

MuPDF Usage:

Right click on a PDF file and select to open with MuPDF. Then you’ll get the mupdf main window:

Left click to pan, right click to select and copy text. Hold down shift when scrolling to zoom. Your navigation history is saved when following links, use ‘T’ to go back.

L, R rotate page
h, j, k, l scroll page
+, – zoom in or out
w shrinkwrap
r reload file
. pgdn right space next page
, pgup left b previous page
skip back/forth 10 pages
m mark page for snap back
t pop back to latest mark
1m mark page in register 1
1t go to page in register 1
123g go to page 123
/ search for text
n, N find next/previous search result
c toggle between color and grayscale
Rendering tool to convert a PDF file to a series of image files.
Tool to rewrite PDF files. Can be used to repair, decrypt, and decompress PDF files.
pdfshow, pdfextract, pdfinfo
Debugging tools to show internal objects, extract fonts and images, and display information about resources in a PDF file.