> Plan antivirus scanning for Outlook 2010

http://technet.microsoft.com/en-us/library/hh550032(v=office.14).aspx

Quotes:

-  If you use antivirus software to perform file-level scanning [Outlook files], while Outlook is in use, data corruption issues might result.

- We we do not recommend that you scan *.pst, *.ost, and other Outlook files directly. Instead, we recommend that you scan email message attachments on the email server and on the Outlook client computer.

> Outlook 2007/2010 – More precisions about Antivirus exclusions and things that can slow down your messaging client in general

http://blogs.technet.com/b/samdrey/archive/2012/10/10/outlook-2007-2010-some-basic-advice-if-you-experience-startup-latencies.aspx