After fresh install, Ubuntu is configured with default apt sources.list, and when running "sudo apt-get update", it fetches urls like "http://cn.archive.ubuntu.com", which is usually slow.

To switch to faster sources, you can change to other sources like 163, sohu by running GUI tool software-properties-gtk, which is very handy, but if you are in a minimal installation of Ubuntu and don't want to install whole dependencies of software-properties-gtk, here's what to do:

1. Assume you have another Ubuntu installation having software-properties-gtk, run it, and find the fast source, e.g. http://mirrors.sohu.com

2. Get its IP address by "ping mirrors.sohu.com", getting result e.g. 221.236.12.140

3. Put this IP in /etc/hosts of the minimal Ubuntu like: "221.236.12.140 cn.archive.ubuntu.com"

4. Now run "apt-get update" and "apt-get install ", and enjoy the speed !