Yes, SHORTHDR will help.  So will DIGEST.  If your server is
being dragged down, consider non-prime time distributions
(a list definition keyword).  Effectively, a DIGEST distribution
can do a non-prime time mailing too.
 
Depending upon how chatty the list is designed to be, you
might consider REPLY-TO= SENDER,RESPECT.  This will tend to cut
down on list distributions.