If you’ve ever wondered just how much effect a TFS proxy will have on your TFS performance, the article linked below might help give you some perspective.
I find this information to be very helpful when discussion TFS performance with customers. Some seem to feel that it’s imperative that a proxy be installed in their environment (this seems to be due to experience with past SCM systems (Rational) that virtually required their multi-site setup to be implemented for remote teams).
I highly encourage you to take a look at this article, which addresses the following points:
Here’s the article link: http://www.codeproject.com/KB/architecture/TFSProxyEfficiencyTesting.aspx