Have you ever wondered why Apple is moving from AFP to SMB2?
Well, here’s one example:
If you are connected to an AFP server (either OS X or netatalk) and you duplicate a really large file the complete AFP connection on the client stalls. In the background the client instructs the server to duplicate the file. However it blocks until the copy process is finished. This is a good idea implemented poorly. It causes all applications doing I/O operations on the sharepoint to either freeze until the operation is finished or even crash.
The best part: If you are using SMB you can duplicate files and don’t hang your applications. I could verify this behavior down to OS X Lion. Maybe it’s even true for Snow Leopard…