To improve the performance of Communications Express when Calendar Server accesses the LDAP directory server, index the following LDAP attributes:
icsCalendar. The attribute is used to search default calendars for a calendar user or resource. Specify the index type as presence (pres), equality (eq), or substring (sub).
icsCalendarOwned. The attribute is used to search for a subscribe operation when the LDAP CLD plug-in is enabled. Specify the index type as presence (pres), equality (eq), and substring (sub).
mail and mailAlternateAddress . These two attributes specifies a user’s primary and alternate email addresses.
The comm_dssetup.pl script adds indexes for icsCalendar , icsCalendarOwned, mail, and mailAlternateAddress attributes.