>Both are running majordomo, so I don't think that's a factor.

FreeBSD uses bulk_mailer along with majordomo; this splits up the mail queue
so you have a bunch of sendmails running at once.  Also, I believe that have
a bunch of exploders all over the country that help distribute the load.

As other people have mentioned, running a bunch of sendmail processes probably
won't help out pain any.  I'd be willing to help out if the idea of exploders
was ever implemented.  Anybody else willing to donate machine resources for
NetBSD exploders?  I don't speak for core, of course, but if we get a bunch
of people saying, "Yeah, sure", it might gain enough momentum for critical
mass.

--Ken