~/.muttrc: set sleep-time 0 for awesome fast mailbox switching.

Thanks @paulrouget! :)

.muttrc

set spoolfile="+lu/INBOX"
set postponed="+postponed"
set record="+lu/INBOX.Sent"
set sleep_time = 0 # faster mailbox switching
mailboxes ! +lu/INBOX.Sent +lu/INBOX.Drafts
mailboxes +htwk/INBOX