In my newsfeeds i found this nice article on Webupd8 about MuPDF and how to install it. You can install MuPDF by adding the Guilhem Lettron PPA for MuPDF to your sources.
MuPDF is a lightweight PDF and XPS viewer MuPDF is also small, fast, and yet complete. It supports PDF 1.7 with transparency, encryption, hyperlinks, annotations, searching and more. It also reads OpenXPS documents. Read more about MuPDF.
To add the PPA and install MuPDF open a terminal window (press Ctrl+Alt+T) and copy+paste the following lines:
sudo add-apt-repository ppa:guilhem-fr/mupdf
sudo apt-get update
sudo apt-get install mupdf
When MuPDF is installed you can close the terminal window and to start MuPDF press the SuperKey and type mupdf
Source: Webupd8 – Quickly Open Large PDF Files Even On Slow Machines With MuPDF.