One of the oft-mentioned improvements in Visual SourceSafe 2005 is what is affectionately called the "LAN booster" service. Configurable in the SourceSafe Administration tool under Server/Configure in the LAN tab, it can be enabled by checking the misleadingly titled checkbox "Enable LAN service for this computer".

After you've checked and applied, you'll notice a new process running - SSService.exe (appearing as a new service - Visual SourceSafe LAN Service - running under the LocalService account in your service manager).

There are a lot of claims that this module is doing wonders for performance - for instance that it is stream-compressing all of the content on the wire, improving the speed "3-5x!". However, after some analysis I've determined that it's doing nothing of the sort.

• Like the web service, it is only used by the Visual Studio plug-in. If you're using the SourceSafe GUI, local or remote, it is unused, and it's 100% the same old SMB file-database.
• It is basically a short-cut - If it's available (it is probed at an RPC endpoint), the Visual Studio 2005 plug-in will get it to assist in a couple of scenarios. For instance if you do a get latest, Visual Studio will ask it which files are newer, communicating back and forth: The (correct) presumption being that it is local so it'll have faster file-system access. The remote plug-in will get a yay or nay if there are newer files, and will then do the pertinent file share accesses.
• All actual file traffic occurs with the same old traditional SMB.

In other words the "LAN Booster" doesn't make SourceSafe an actual client-server source control system (the Internet web service sort-of does for a limited set of purposes, and again only with the plug-in in Visual Studio 2005), and its performance improvement is marginal at best in real world use.