This is an enhancement request.

The goal of short-circuit rules is to stop furhter rule processing and save the 
processing time.  If you make a net rule a short-circuit rule, it probably 
won't by default do much good, since net scores are harvested late in the game 
to give them time to arrive.

If you make a meta rule with a dependency on a net rule, and then give the meta 
both a high (negative) priority so that it runs very early and make it a short-
circuit rule, it should block processing of other non-net rules until the 
dependency net rule can be evaluated, or times out.

This would have the effect of lengthening the time to process a mail message, 
but could reduce the overall processor time for the message by eliminating most 
rule processing.  It would also have the ability to insure that the message 
doesn't get marked as spam if the rule is essentially nice itself.