I'm reviving the topic since i've encountered the exact same problem : after upgrade to OSX mavericks, my portable thunderbird started to hangs forever on startup (I had to wait 10 min before it asked for contact permission and then open up)
I've found a solution by accident. So I have mavericks (10.9.3), portable thunderbird and it hangs. I had to used diskwarrior to rebuild the directory and on restart of the mac, portabe thunderbird opened up in a flash. Problem solved.
EDIT : this seems to have worked only once for me, the first time after i restarted after the directory repair… after that, same hanging on thunderbird startup…. :(