Ubuntu has a great network of mirrors all over the world, allowing you to download updates from a server geographically close to wherever you are. However, in the age of broadband, the speed of your connection and how close you are to a server has less to do with the speed of downloads than the speed and capacity of the server you are downloading from. Some sites have amazingly fast servers, and some sites have horribly slow ones. Installing new software from the Ubuntu repositories can be made considerably faster by using Synaptic Package Manager to choose the best server.
For some reason, Synaptic has almost hidden this little gem. To get to it, click on the "Settings" menu, then select the "Repositories" menu item. This will open a new window with a selection of options. Next to "Download From:" there is a drop down menu, if you select "Other..." that will open a new window showing a list of all of the mirrors that Ubuntu knows about, and a button that says "Select Best Server" and Synaptic will begin the testing.
Software sources window:
Choosing best server window:
Read more at Ostatic