copy file using UNC paths is very slow

This is our scenario. We have 2 servers, one IIS and one SQL. The SQL server
issues command line copy commands to copy files on the IIS server using UNC
paths. An example of the command line call issued from the SQL server is:

Copy \\IIS\ShareName\SourceFile.ext \\IIS\ShareName\SourceFile2.ext

We are finding that this operation is taking a very long time. For a 4mb
file it takes upwards of 5 minutes to finish copying. If we try this copy
operation from another server, say Server2 with a copy command as follows:

Copy \\Server2 \ShareName\SourceFile.ext \\Server2
\ShareName\SourceFile2.ext

It takes only 7 seconds.

Due to this we suspect that the problem lies in the SQL server. The SQL
server has plenty of RAM left (about 600 mb) and processor load is never
over 10% on the Quad Xeons.

Any ideas what this might be?


Thanks,

Caine