Swiftfox is the Firefox web browser, but built with optimizations to increase speed on specific CPU types. It is compatible with all Firefox extensions and themes, and uses the same settings location as Firefox, so you can use both transparently.

Instructions from getswiftfox.com

• Add the Swiftfox repository

          sudo gedit /etc/apt/sources.list

• Add this line at the bottom

          deb http://getswiftfox.com/builds/debian unstable non-free

• Update apt sources

          sudo apt-get update

• Check your CPU compatibility here
• Install your version of Swiftfox

          sudo apt-get install swiftfox-pentium4

• Run with

          Programs > Internet > Swiftfox

• There is also an [installer] available that is distro independent. It is a script that downloads and installs Swiftfox in the /opt directory and attempts to use existing Firefox plugins. The installer is probably the best way for most non-Ubuntu and non-Debian users to install Swiftfox.