Visual Studio TFS very slow

It so happens that in Visual studio, the connection to a TFS server is through a possible proxy server. (A default one) 

If you VS is slow to take TFS,

go to the

Visual Studio 10.0/Common7/IDE/devenv.exe.config file

go to the bottom

locate <system.net>

and add

  

    <system.net> 
    <defaultProxy enabled="false" /> 
        <settings> 
            <ipv6 enabled="true"/> 
        </settings> 
    </system.net> 
    <appSettings> 
        <add key="TestProjectRetargetTo35Allowed" value="true" /> 
    </appSettings> 
</configuration> 

   this will stop it from looking for your TFS server on the internet

From http://mperlstein.blogspot.kr/2012/02/visual-studio-tfs-very-slow.html