Apt-fast is a 'shell script wrapper' for apt-get that uses a download manager such as axel to open multiple connections to the update server and download small parts of the required file and then recombine them. It thus speeds up the downloads of packages tremendously.
The original author of apt-fast was Matt Parnell, who invented it in 2008; he explains it here on his own site. However, the project's home is now at Github and anyone can contribute to it.
It can be installed from Git or from a ppa, although the latter is easier and may be more stable. The stable ppa from the official Launchpad one is regularly updated. You must also have installed a compatible download manager such as axel or aria2c.
You now use apt-fast instead of apt-get until you uninstall it:
sudo apt-fast update && sudo apt-fast upgrade
sudo apt-fast install program
An article that explains further how the program works is at howtogeek.
