Windows 7: Slow IMAP syncing

Hello,



I'm using Outlook 2010 (Exchange protocol) and WLM (IMAP) to access the same Exchange 2010 mailbox. When I move/delete mails in Outlook, the changes reflect almost immediately in WLM. But if I move/delete items in WLM, it takes ages (up to 1 hour) for the changes to reflect in OL. So apparently WLM is doing very slow updates on the server side, although the send/receive interval is set at 5 minutes.
Also I notice that when I delete a message from a folder, the number of items marked on the status bar is decreased but in the folder properties it remains at the previous number for a long time (actually till it syncs).
What could be happening?
tia, chris