At a client we were testing our newest line of development machines. After installing Visual Studio 2010 we noticed that the performance was VERY slow when connecting to Team Foundation Server (2010). Performing a get latest of a large solution took several hours(!).
Some investigation showed that it does not appear to be a TFS issue per se but rather something lower in the .NET Framework stack, having to do with automatic proxy discovery through the WPAD protocol.
You can work around the issue by turning off proxy autodiscovery on a per-application basis by using a .exe.config setting.
The .exe.config for Visual Studio is %VSINSTALLDIR%\Common7\IDE\devenv.exe.config and it already contains a section in the .exe.config for System.Net. After adding the defaultProxy element, that section would look like this:
1: <system.net>
2: <defaultProxy enabled="false" />
3: <settings>
4: <ipv6 enabled="true"/>
5: </settings>
6: </system.net>
Issue solved!