spam_clean_day: (5 min avg)
Max spam: 1304.0 msgs Average spam: 489.0 msgs Current spam: 516.0 msgs
Max clean: 7224.0 msgs Average clean: 1309.0 msgs Current clean: 1357.0 msgs
Ok, that's better. I know what I'm looking at now.
What makes you think this is a performance issue? The fact that you're getting more HAM than SPAM? or what?
Do you have any front-end RBLs, Greylists, or other MTA layer filters that are filtering out some of the spam before it gets to MailScanner in the first place? (This would severely bias your numbers)