In the past, we’ve turned on compression for the SOAP responses for the TFS web services.  In TFS 2010, you must do it manually.  In the future, I hope we have it turned on by default.  It’s particularly good for teams that aren’t at the same location as the TFS server.  For users on a high-speed corporate network, it’s not likely to matter.

Grant wrote a post on how to turn it on: TFS2010: How to enable compression for SOAP traffic.