OS X :: Mail Hogging CPU In SL?

I did a standard install of Snow Leopard (SL) and everything seemed fine for a while... but I noticed a lot of beachball time, and the computer became more and more unresponsive. I found then that Mail was hanging on me... immediately after start-up it seemed to work fine, but after about three minutes of working I could no longer compose emails, and the panels displaying inbox, or whatever, contents would not display their contents... even though I knew they were not empty! I also tried to quit Mail to refresh it, but found that it was not possible... I had to resort to force-quit Mail. Moreover, if I wanted to shut down Mail would not quit and i had to force quit before I tried to shutdowN... every time! After a few abortive sessions I stopped Mail being a log-in item and found that everything ran fast and smooth UNTIL I loaded Mail... after which the whole of the above scenario would repeat... I then decided to look in Activity Monitor and found that Mail was listing between 90% and 120%+CPU usage!!... even when it was in the background and not being overtly used. When I did manage to quit it, after it had left the desktop and switcher, it was still listing 20% or so CPU usage.

I decided to try a different client, and loaded Thunderbird. Runs great... and so does Snow Leopard all the way round now!! But I don't really want to go over to Thunderbird... I would rather stick to the integration level possible with Mail. I hope that some form of patch will be found to correct this behaviour. (By the way, I have always had some problems with Mail cancelling shutdown even before SL came onto the scene!)