Resources:

Visual SourceSafe Optimize Performance

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/guides/html/vstskoptimize_performance.asp

HOWTO: Use SourceSafe Over a RAS or ISDN Connection

http://support.microsoft.com/default.aspx?scid=KB;en-us;q158219

Visual SourceSafe Frequently Asked Questions

http://www.michaelis.net/SourceSafe/Faq.htm

Notes:

1.  Make sure VSS is using your local machine for temporary files, not the VSS server as is the default.

Folders for Temporary Files

Specifies where you store temporary files. The default setting is to store temporary files on the server, but your administrator can also set the Temp_Path variable in your SS.INI file to a local folder which speeds up operations like viewing files. For example:

Temp_Path = c:\windows\temp

2.  Disable any kind of Anti-Virus Auto-Protection software (e.g. NAV AutoProtect) while using VSS, or change its filtering to exclude the VSS database at the client end. This will have a dramatic effect on performance.

3.  Use a VPN which includes compression (e.g. PPTP).  IPSec does not, AFAIK.

4.  Use of pinning in VSS seems to have a huge negative effect on performance.  Sharing also, but to a lesser extent.