Install this February 2009 Cumulative Update for Outlook 2007:
1. Install the update – Download page (e-mail registration required)
2. Read about What’s in the update – February CU Whitepaper
3. Read about Outlook Team post on the update – Outlook Blog
I would say it is a massive world of performance difference after installing this. I launch Outlook in a few seconds now and switching between folders is wickedly fast now. Searching for emails is even faster. Kudos to the Outlook team for updating Outlook 2007.