Slow login (Active Directory User + Filevault2) - Mountain Lion
Think I found an answer: https://jamfnation.jamfsoftware.com/discussion.html?id=6025

sudo defaults write /Library/Preferences/com.apple.loginwindow DSBindTimeout -int 8

Changes the bind timeout to 8 seconds. Our bind happens within 3-4 seconds over ethernet, so we figure double it and add an extra second should be enough for an absolutely unscientific unengineering-like guess.