New W2008 Server with S-L-O-W connection to IFS

All,

We have a relatively new 64-bit W2008 Server (virtual) acting as a terminal
services server and we're having a performance issue. Call this server
RDS. It replaced a 32-bit W2003 Server (also virtual).

A few days ago I posted briefly about this issue (SMB vs SMB2), speculating
that SMB2 was the culprit. RDS was changed/booted last night to use SMB
instead of SMB2 with no performance improvement, so SMB wasn't the issue.

An example of what is going on. We create PDF copies of all invoices
(created on the System i) automatically and store them in the IFS. At
month end they get moved off the IFS and onto a windows server (also
virtual).

To make it simpler to view a PDF invoice from green screen, I put a link to
the PDF on various inquiry screens as hotspots. If the invoice is from the
current month, the link points the the proper file on the IFS. If the
invoice is prior to this month, the link points to the proper file on
another Windows server. So the user need only click on the link on the
green screen and the PDF is opened up. This worked well for many years
with the old terminal services server, but now performance is abysmal.

To summarize RDS behavior:

1) If I click the link on green screen:
a) If the file link is to the IFS, it takes 60 seconds to open up
b) If the file link is to the Windows file server, it takes 2-3
seconds to open up

2) If I paste that link into a browser:
a) If the file link is to the IFS, it takes 2-3 seconds to open up
b) If the file link is to the Windows file server, it takes 2-3
seconds to open up

So everything is fine except 1a. And only RDS exhibits this behavior. The
old terminal services server never did, nor do any PC workstations.

It is worth noting that if one opens a spreadsheet file (.xls) on the IFS
via Excel 2003 in RDS, it also takes forever.

The differences between the old terminal service server and RDS are: 1) RDS
is 64-bit vs 32-bit, and 2) RDS is W2008 server vs W2003 server.

Ideas?

Thanks.