Some important information for the Team System Web Access administrators. If your TSWA account does not have full permissions to the HKLM\SOFTWARE\Microsoft\VisualStudio\9.0\WorkItemTracking\Cache registry path, you may be wasting a lot of resources. The work item store object stores the cache stamp there which is used on subsequent connect to determine what metadata should be obtained from the server and cached locally. If that key is missing, connecting to the server will pull its entire metadata.
That's right. Every time a new user connects to the server using web access, TSWA downloads the entire metadata (tens or even hundreds of megabytes) just to throw them away.
To fix that you should grant TSWA account full permissions to the abovementioned registry path.
This issue appears in VSTS 2008 and 2008 SP1. We're working on a fix for that issue in dev10; we're planning to change storage mechanism so that saving the cache stamp will work with the default TSWA permissions.