Outlook 2007 Contact Items open Very Slowly from Vista Search

When using the Vista search (Windows Desktop Search) to search for contacts
in my Outlook 2007 profile, the search results come up quickly, but when
clicking on a contact to open it, it takes a really long time to open - even
though Outlook is open at the time. (Between 10-15 seconds on average.)

The Outlook contact items I am searching are in my Outlook Public Folder
Favorites - it is a public folder full of about 2000 contact items.

Performing the same search from within Outlook does not have the delay - the
search is equally fast and contact items open immediately.

When searching for other types of items (documents, pictures, music), the
files open quickly. Only Outlook items open slowly.

I've done a lot of searches looking for why this might be slow, and tried a
lot of suggestions, including:

* Minimizing the size of my Outlook profile (it is currently just 11 MB - or
11218 KB, according to Outlook's "Mailbox Cleanup Wizard"), so it's not
because I have a very large profile.

* Re-built the Windows Desktop Search index

* Excluded items from the Windows Desktop Search index that I don't want
indexed

* Left the indexer running overnight so it could build a complete index
(again, the search is fast - it's opening the results that's slow)

* Restored all of Outlook's file type associations

So far, none of these has helped. Opening items is still as slow as ever.

Some additional facts about my particular configuration:

* My mailbox uses an .OST file, not the older .PST file.

* I am running against an Exchange 2003 server, in Cached Exchange Mode. I
have turned on the option to "Download Public Folder favorites."

* I'm running Windows Vista Ultimate 32-bit, with all the latest updates &
service packs as of the current date (March 18, 2009). Microsoft Office 2007
is equally up-to-date with all the latest updates and Service Pack 1.

* I upgraded to Vista recently from XP Media Center Edition. I used Windows
Desktop Search there as well, under the same Outlook configuration. I did not
have the delay when opening Outlook items then - only after upgrading to
Vista did this begin to happen.

I've exhausted all my usual troubleshooting steps at this point, and I'm
still at a complete loss as for why Outlook items take so long to open from
Vista Desktop Search results.

If anyone has any ideas for why this is happening, or suggestions for what I
can try to get to the bottom of this, please let me know - I'd really
appreciate it!

Thank you!