30,000 doesn't sound like a huge no. (I've 100,000+), and I think any decent email client today should handle that amount of mail reasonably well.-mwang
No...30,000 doesn't sound like a huge number and you would think that any decent email client in the year 2009 would handle that amount of mail reasonably well...but they don't.

Most email clients have database issues if you try to store too many emails (Outlook I'm looking at you!) or store emails in a 1-email-per-file arrangement which gets around the database issues, but really bogs the clients down when you start trying to deal with massive amounts of messages.
Your method is probably the way of the future for those of us who deal with huge email archives, but most people don't keep any emails for any length of time which is probably why email clients today are still having trouble with huge email archives. It's just not a feature that is in high demand.
But enough of the off-topic banter. It's detracting from f0dder's escape from The Bat!.