@scald I am experiencing slowness on mapped domains as well. In the network tab I am not seeing that link using an ip in chrome. In the admin it will not save state on the remote login box.
When I echo get_site_option( 'dm_ipaddress' ) I get an the correct ip
Echoing get_site_option( 'dm_remote_login') displays 0
Strange stuff here. Main blog loads quickly but mapped domains take 10s or so.
I am not using any caching plugins