Sometimes when I have to clone a huge repository from Github, I find that the fetch speed can be extremely slow (KB/s).
There are two tricks I try for a quick cloning:
Kill the command and try again. Do this a few times, see if you can get a faster connection. This works most of the times.
Fetch only the latest revision first and then fetch the rest:
$ git clone --depth=1 firstname.lastname@example.org:joe/hello-world.git $ cd hello-world $ git fetch --unshallow
Tried with: Git 1.9.1 and Ubuntu 14.04