I have just discovered that composing message in plain text rather than HTML solves the issue. User2 indeed was the only one with "Compose message as HTML" enabled.
-- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/682136 Title: Thunderbird script busy when composing new message -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
