However, it still takes time (up to 10 minutes) for final delivery, because there is a mail processing queue in which the mail has to enter, be examined (even minimally) and be returned. Amavis is taking time because clamd scan is time consuming and it is processing mails which are ahead (in queue) of the mail we want to expedite.
As Bastian pointed out, your mail sample passed Amavis within a few seconds. If those received timings are typical for your problem, forget about micro-optimizing Amavis.
