All of these lists are a few hundred members or less, though. I'm still not really happy with my stats gathering currently, but I'm not sure what I'm looking for. I imagine I will end up writing my own program to parse the sendmail syslogs, which currently run 20 to 25 megs of raw log entries per day. Interesting to me is that the CPU usage is nothing. This is not necessarily 'nothing'.
Load average is how many processes are ready to run.
Corrections and comments welcome. We found the problem by manually telnetting to the SMTP port the problem machine. The sendmail on my machine also had a 70 second timeout, so it was a race. The load average has absolutely no correlation with CPU usage. You can't use load or CPU as a list performance metric.