If Outlook 2007 has been running slower then usual you can try disabling Add-ins that are not being used.
To do this Open up the Trust Center by navigating to Tools –> Trust Center on the menu.
On the left-hand pane, choose Add-ins, and then near the bottom of the window you’ll see a button that will let you manage your COM Add-ins.
From this window you can disable any addins that aren't in use. Here are some I've disabled...
- Microsoft Exchange Unified Messaging - Disable this if you aren't using Exchange.
- Microsoft Office SharePoint Server Colleague Import Add-in - Disable this if you aren't using Sharepoint.
- Microsoft Outlook Mobile Service - Disable this if you are not sending text messages from Outlook.
- iTunes Outlook AddIn - Disable this if you are not syncing your calendar or contacts with an iTunes device.