With the increased concerns over viruses spreading over the Internet and through e-mail, many anti-virus software companies have implemented a feature that scans every file every time that the file is opened. This feature can have a dramatic impact on Visual SourceSafe (VSS) performance. This feature is sometimes referred to as Auto-Protect or Auto-Scan.
Because Visual SourceSafe is made up of many small file pairs, when you do a branch or other large scale Visual SourceSafe operation, the Auto-Scan feature can have a dramatic effect on performance. In one case, a branch performed on a VSS project with this feature enabled took eight hours; with the feature disabled, it took 20 minutes.
This feature can have such a dramatic effect because the operations are happening across the network and are affected by network performance. At the same time, they are also affecting other users' network performance.
Many of the anti-virus software companies allow you to configure what file types are scanned with these features.
Microsoft Visual SourceSafe support recommends that you enable virus checking without the Auto-Scan option on the Visual SourceSafe server, and only do a full scan of the files on the SourceSafe server periodically.