Agents and Clients are 8.0.2 running on Windows

Ok, I had hoped this would just go away since it seems more like a workstation issue than anything else. So, sorry to waste a few kilobytes in the forums, but here's our issue...

Last summer we upgraded our GroupWise 7 system to GroupWise 8.0.2 HP2. We replaced the NetWare 6.5 servers with Windows 2008 Standard. The PO's are physical boxes (new, at the time, IBM's), and we VM'd the domains and gateways. Task Manager...Performance shows that these servers, generally, spend their time idling. The PO's barely do anything. The domains have occasional spikes, but nothing steady. And the only one that's given me specific trouble has been the GWIA when there's a corrupt message in a queue.

We also run NotifyLink and have a BES server for phone syncs. These have been in place since before the upgrade. We recently installed Novell Data Synchronizer to test it out, but the issues were occurring before this was installed.

The Problem:

I've had a dozen or so users report that it takes a "long time" to move items between folders in the GW client. The only solid piece of a clue I've found is that a restart of the POA service makes it all go "fast" again. I don't see anything definitive in the server or POA logs. I've seen it myself but not always at the same time that others report the problem, even if we're on the same PO. They can be moving one or several items at a time.

One guy had a rule that triggered on a folder open/close, removed the rule and all was well, for a while. Then it returned. Even went so far as to move him to a different post office (maybe a "defrag" of his mailbox would help), and it was good, for a while.

I've seen it on PC's and notebooks so I don't see a specific connection there. All are Windows XP. People are in different departments so local applications are different, mostly.

I can also say that all of the users that I've heard of are on two post offices. One (mine) has 1698 users, 33 resources, 15 distribution lists, 1 library, 1690 mailboxes, 345 inactive mailboxes and the other has 1796 users, 24 resources, 4 distribution lists, 0 libraries, 1792 mailboxes, and 597 inactive mailboxes. (Yeah, that's a lot of inactive mailboxes. It's not my call on how to deal with them unfortunately.) Most of the phone sync people are also on these two post offices.

I'm not convinced it's GroupWise, to be honest, so at this point I'm mainly wondering if others have seen this when running their GW system on Windows servers. And if so, what clues do you have?