[Dovecot] repeating dsync - questions

[Bob Gustafson]

I am still on my quest for a quick way to move mail from a live Maildir
system to a 'soon to be live' sdbox system.

I copy Maildir to new system using:
rsync -ar --times hoho4:/home/bobgus/Maildir/ /home/bobgus/Maildir

Then I convert from Maildir to sdbox with:
dsync mirror maildir:~/Maildir

Then I copy more messages from live system using rsync
Then I do the 'dsync mirror maildir:~/Maildir' again

There were only a few messages that were copied over in the 2nd rsync
pass and it went quickly, but the 2nd dsync pass is taking a long time.

Also, I see strange directories in the sdbox directory (see below)

Is this normal? Why is it taking a long time? (debug is set..?)
See dovecot -n below

Thanks for your time

Bob G

[bobgus at hoho0 ~]$ du -h sdbox
4.5G	sdbox/mailboxes/Sent_09e4633955496151c51a0000ba55d82c/dbox-Mails
4.5G	sdbox/mailboxes/Sent_09e4633955496151c51a0000ba55d82c
8.0K	sdbox/mailboxes/Apple Mail To
Do_0ee4633955496151c51a0000ba55d82c/dbox-Mails
12K	sdbox/mailboxes/Apple Mail To Do_0ee4633955496151c51a0000ba55d82c
358M	sdbox/mailboxes/Drafts/dbox-Mails
358M	sdbox/mailboxes/Drafts
4.5G	sdbox/mailboxes/INBOX_f9e3633955496151c51a0000ba55d82c/dbox-Mails
4.5G	sdbox/mailboxes/INBOX_f9e3633955496151c51a0000ba55d82c
88K	sdbox/mailboxes/Important/dbox-Mails
92K	sdbox/mailboxes/Important
...
...
=====
[bobgus at hoho0 ~]$ dovecot -n
# 2.1.15: /etc/dovecot/dovecot.conf
# OS: Linux 3.8.5-201.fc18.x86_64 x86_64 Fedora release 18 (Spherical
Cow) 
auth_debug = yes
auth_mechanisms = plain login cram-md5
auth_verbose = yes
disable_plaintext_auth = no
first_valid_gid = 1000
first_valid_uid = 1000
mail_debug = yes
mail_location = sdbox:~/sdbox
managesieve_notify_capability = mailto
managesieve_sieve_capability = fileinto reject envelope
encoded-character vacation subaddress comparator-i;ascii-numeric
relational regex imap4flags copy include variables body enotify
environment mailbox date ihave
mbox_write_locks = fcntl
namespace inbox {
  inbox = yes
  location = 
  mailbox Drafts {
    special_use = \Drafts
  }
  mailbox Junk {
    special_use = \Junk
  }
  mailbox Sent {
    special_use = \Sent
  }
  mailbox "Sent Messages" {
    special_use = \Sent
  }
  mailbox Trash {
    special_use = \Trash
  }
  prefix = 
  separator = /
}
passdb {
  args = scheme=CRYPT username_format=%u /etc/dovecot/users
  driver = passwd-file
}
plugin {
  sieve = ~/.dovecot.sieve
  sieve_dir = ~/sieve
}
protocols = imap
service auth {
  unix_listener auth-userdb {
    mode = 0777
  }
  user = root
}
service imap-login {
  vsz_limit = 128 M
}
service imap {
  vsz_limit = 768 M
}
service managesieve-login {
  vsz_limit = 128 M
}
service managesieve {
  vsz_limit = 768 M
}
ssl = required
ssl_cert = </etc/pki/dovecot/certs/dovecot.pem
ssl_key = </etc/pki/dovecot/private/dovecot.pem
ssl_require_crl = no
userdb {
  args = username_format=%u /etc/dovecot/users
  driver = passwd-file
}
[bobgus at hoho0 ~]$