In a previous tip, I said:
"As your folders (and the mailbox) grows, it tends to slow Outlook down, so while you can have 65,000 contacts, you may not want quite that many."
David asks, "Okay then, what slows Outlook more, a few messages in lots of folders, or lots of messages in a few folders?"
The answer is… "It depends."
If you are searching for an item and know which folder it's in, fewer items in the folder equals a faster search. While searching more folders won't take any longer than searching many items in one folder, it's often easier to find the items without searching if you use fewer folders.
Overall, Outlook is affected more by message store file size than item counts. A 300 meg pst, whether it has one folder or 300 is going to use more resources and slow Outlook down more than a 30 meg store.
Note that newer computers can easily handle Outlook and large message stores, so there is no need to reduce your message store to 30 megs. :) If you use Outlook 2002 or older you do want to keep your personal folders under 1.75 GB though.
Published December 30, 2003. Last updated on September 13, 2014.