Optimizing Public Folder Performance
Public folders can be lightning fast or painfully slow - it's your choice. Outlook 2007 and Outlook 2003 make it optional whether you want the data in your favorite public folders downloaded and cached on your machine for fast access.

The two check boxes seen in this dialog, Download shared folders and Download Public Folder Favorites, are not checked by default. You need to open this dialog and check both of those boxes. Note the Outlook 2003 version of this dialog does not include the option to download shared folders.
- In Outlook 2007 this dialog is found under Tools, Account Settings, Change, More Settings, Advanced.
- In Outlook 2003 this dialog is found under Tools, Email Accounts, View or change existing email accounts, Change, More Settings, Advanced.
If you do not check the box to download public folder favorites, every time you click on the public folder, its entire contents will have to be pulled from the server, through the Internet, to your machine. That of course, is a painfully slow process.
You also need to add the public folders you use to your 'favorites.' Right click the public folder icon and choose add to favorites, or drag and drop the folder onto the favorites icon. See the illustration below.
This also allows you to use the public folder when you're offline. Here are the steps to setup a public folder for offline use and fast access at any time.
First of course, you must configure Outlook in cached Exchange mode. See Outlook Setup if you need details about that.
1. Add shortcuts to your public folder favorites for the public folders you use
- If the Folder List is not visible, click the View menu, and then click Folder List.
- Click Public Folders, and then click the public folder you want to add as a shortcut to the Favorites folder.
- On the File menu, point to Folder, and then click Add to (Public Folder) Favorites.
- To change the name of the public folder that appears in your Favorites folder, type a new name in the Favorite folder name box.
- To add shortcuts to subfolders of this public folder, click Options, and then select the options you want.
For help on an option, click Help.
- Click Add.

Don't be confused by the apparent presence of two copies of each folder. The icons in the Favorites section are only shortcuts, not duplicate folders. There is only one master copy of each folder, and that is on the server. Clicking the icon in the favorites section will pull up the main and only copy of the folder. If you have selected the option to Download Public Folder Favorites, your machine will have a local copy of the folder, but the local copy is only a cache to speed up your access.