Comment 7 for bug 1001138

I've now managed to reproduce this in a fresh user account. It seems that after making a new account if you immediately log in to gnome classic it will log in instantly. You can do that over and over and it is always fast. But as soon as you have logged into a Unity session, both Unity and Gnome Classic logins become extremely slow. It may also work the other way.

Here is the bootchart of Unity with fresh user after I've triggered the bug.