Question about Outlook Express

In my office I have 3 Macbook Airs (Bought with Lion pre-installed), all using Outlook 2011 with Exchange. All three of them have an issue where they will hang for 30+ seconds every few minutes (showing the spinning beach ball, also known as the spinning rainbow pinwheel of death), although one has it less frequently. I have scoured the web to find a solution but of everything I've tried nothing has solved it.

The setup:

All three Macbook air computers, all with Lion OS X Installed and Office for Mac 2011 and update 14.2.4

Our exchange setup is as follows:

User 1 has access to their own mailbox as well as our technical support inbox, our filed mail and main company inbox and User 2's inbox.

User 2 has access to their own mailbox as well as our technical support inbox, our filed mail and main company inbox and User 1's inbox.

User 3 has access to their own mailbox as well as our filed mail and main company inbox

These are set up using ‘Delegates’

As it stands, the inboxes for the accounts are as follows:

Technical support inbox:

Several subfolders with 20-30 emails in.

Filed mail:

Important mail with 2000+ emails in various different folders.

Main company inbox:

Important mail with 1000+ emails in various different folders.

User 1, 2 and 3's Inbox:

Several subfolders with 20-30 emails in.

The Problem:

When using outlook on a day to day basis it hangs every minute or so for 30+ seconds, which has gone up to 15 minutes at points.

During the ‘frozen’ time, mdworker, mdworker32 and Microsoft Database Daemon all take it in turns to use 90% or more of the CPU until outlook unfreezes and becomes usable, at which point these processes disappear.

Looking into this, I found that the mdworker files are associated with spotlight, Lion’s inbuilt search feature, so looked into that issue and, as a result, we have removed all non-essential emails, deleted the local caches for all the mailboxes and re-synced the mail from the server and currently stand at a bare minimum of email numbers (So we cannot remove any more and the local copies are accurate) in an attempt to reduce the amount that spotlight is indexing.

Things I have tried to solve the issues we are experiencing:

Everything detailed in this KB: http://support.microsoft.com/kb/2409331

  - Nothing helped the issue.

Re-creating the identity several times (deleting and starting again)

  - This did nothing except cause long wait times whilst mail downloaded

Testing on a new user account (http://support.microsoft.com/kb/2439218)

  - The hangs lessened but returned to full force soon after.

Removing spotlight’s indexing files (Microsoft Office.mdImporter)

  - Seemed to solve the problem but disabled the search functionality of outlook, which is required.

Telling spotlight not to index the Microsoft data folders

  - Didn’t seem to help the issue but made some files un-searchable

Removing all non-necessary emails and re-syncing the accounts to the server

  - Didn’t seem to help

Removing the mdimporter has so far been the only ‘succcessful’ solution in stopping the hangs but the lack of search functionality means that it is not a viable solution to the problem. It would seem that the issue is Spotlight’s indexing features that do not work entirely with outlook but I cannot see a solution without disabling it, which just isn’t viable.

Has anyone got any other solutions?