[Samba] long connect delay over vpn+firewall

[Frank Cusack]

I am connecting to smbd over a vpn connnection.  After tunnelled traffic
comes out of the vpn it hits firewall rules.  Per
<http://www.samba.org/samba/docs/man/Samba-HOWTO-Collection/securing-samba.html#firewallports>
I am allowing

  135/TCP
  137/UDP
  138/UDP
  139/TCP
  445/TCP

through the firewall.  With this configuration, mounting an smb share
from win XP home SP2 takes 2 or 2.5 minutes. If I change the firewall to
permit all traffic, the mount happens right away.

What causes this?

I'm running smbd only, not nmbd or winbindd.

-frank