That worked for me, too! Fortunately there were no valid custom tags that I needed, so I went into the DB back-end and just deleted the entire table contents. Voila, snappy again! 🙂
I get the same problem and I’m using 2.6.3. 🙁
I have the same problem, as I run a WPMU with multi-domains. Did you get postie to work with multiple domains?