Dear Maintainer,

We have many machines that automount home directories on demand; user
authentication is held in LDAP. lightdm as part of its operations seems to
visit (and therefore cause an expensive and slow NFS mount) the home directory
of every user in LDAP, instead of only the user logging in.

This slows things down a lot for logging into a machine.

I'd expect lightdm not to touch any directory other than its own
(for logging and config), and the
currently logging in user's home directory.