Outlook Running Slowly? Try Cached Mode.
Much of the time, email runs slowly because it is operating in "live exchange mode", which requires more resources to run. If your email is behaving sluggishly, try switching it to "cached mode" using the following instructions.
- From Outlook, click the File menu
- Choose Account Settings -> Account Settings
- Click on your email account and choose "Change..."
- Check the box labeled "Use Cached Exchange Mode" under "Offline Settings"