/etc/ldap/slapd.conf can be configured to include the following two
optimization options, responsible for:
Generating indices for frequent queries and updates:
index objectclass eq
index uid,uidNumber,gidNumber eq,pres
Cache LDAP data in memory
# how many attribute values are cached in memory
cachesize 10000
# specifies the size, in bytes, of the space allocated to store database files in memory
dbcachesize 1000000