When a LDAP datasource is not available (LDAP server doesn't respond).

All settings which list LDAP Sources (Populations, Datasources, Contents synchro,) take a while to open associated form. 

It is like LDAP source access is checked every time it is listed, so when LDAP source raises a time out, it can be very long.

When the wrong LDAP source is removed, everything is OK.