Slow enumeration of Domains on Windows 2003 Server

Hi all,
I have a customer with a Windows 2003 Domain where
the member servers are a mix of Windows 2000 and Windows
2003. Most of the member servers are running IIS. The
customer has an asp script which effectively enumerates
the available Windows Domains and puts them into a array
for later use in a dropdown list on a login box. When we
run this script on a Windows 2000 member server, it takes
about 2 seconds to populate the list (about 50 domains).
When we run the same script on a Windows 2003 member
server it takes about 15 seconds to complete.

Has anyone got any ideas why this might be (the network
configuration re: WINS/DNS is the same and the Windows
2003 server performs better in all other ways) and what I
can do to speed up the enumeration of Domains ?

Regards,

Soner