I have a client running Outlook 2007 (cached) in a hosted exchange scenario. His .ost file is about 7.5 GB. The inbox is the lion's share of that size. The inbox itself is 33,000 emails. Also, the Inbox contains 21 subfolder, each holding between 5 and 750 emails.
Clicking from email to email is very slow (as I would expect).
Am I correct in assuming that the best shot at significantly increasing speed is to get all the subfolders out of the inbox, and placing them parallel to inbox (i.e. a subfolder to "Mailbox - <name>"? (And also, I assume, getting thousands of emails out of the inbox itself?)