Hi, We're testing roundcube in a fairly large environment (80K users, 900K mailboxes) with a cyrus imap backend. In our environment, roundcube/iloha imap's namespace discovery phase takes about 1.5 seconds on an unloaded machine. This happens on every email view.
Iloha has the ability to skip the namespace discovery phase if a imap_root is configured and roundcube has a configuration option for imap_root. But the two aren't connected! By handing off the imap_root variable to iloha mail sooner rather than later we cut our time to view a message from 1.7 seconds to 0.2 seconds.
I've submitted a patch with this ticket: http://trac.roundcube.net/ticket/1485172
Please let me know if there's anything I can do to help get this accepted.
Thanks, Ziba