Visual studio 2010 - very slow access to TFS 2008

I've been using Visual Studio 2010 to access TFS 2008 since a while and it has always worked fine until recently where network administrators of my company deployed a new web proxy.

Since then, Visual studio took an awful amount of time to access and retrieve source code from TFS.

After a quick search on the Internet, I found the solution:
http://social.msdn.microsoft.com/Forums/da-DK/tfsversioncontrol/thread/cec1cda4-93ac-404a-96a0-6c45910325ce
To correct the problem, I modified the configuration file of Visual Studio by adding the following line to the System.net section:

defaultProxy enabled="false"

After modification, the System.Net section looked like this: