I just found this one today:

the Outlook 2007 hotfix package (Outlook.msp): February 24, 2009

This package should fix some issue’s in outlook. One thing it is promising is that Outlook will be much more responsive (see this link, this should be in this package).

I requested the hotfix by clicking on the link above the article. When I installed it, the first time Outlook starts it will spawn a dialog stating that it’s preparing outlook. After I restarted Outlook again, I noticed a speed increase in adding a new calendar item (something that would take a long time in my “pre-hotfix” configuration).