I certainaly did not turn connection logging on but the effect was disastrous. Mail would not respond as long as there was a slow connection. I figured this out through turning off all network connections and watching Mail spring back to life and let me search my messages.
Normally if a connection is slow to respond, mail just lets the slow connection do it's thing while everything else operates largely unhindered.With connection logging turned on, your Mail app is a slave to the slowest connection to a mail server (I have 8 total)
I had to crash mail over and over again to do a simple search of my messages until I happen to notice that this connection logging was turned on. I found this thread, turned it off, now Mail works as well as it ever has (very buggy but usable)
How dare Apple do that behind my back!? After all the problems there are Mail, they have the gall to turn on logging and reduce Mail to unusable?
I also deleted all the logs for a good house keeping seal of approvable. They were here:

Some day Apple might consider hiring a test team... instead of relying on all the users.