The GetUserByName counter represents the number of times the Content Engine needed to go to the LDAP server and lookup a user by name. GetUserByName method retrieves user's attributes similar to the following:
ui, cn, mail, objectSid, distinguishedName, objectClass, memberOf.
The memberOf attribute holds the DN values of the groups that this user directly belongs to. If the user is a member of many groups, this method may take a bit more time to finish. The average duration of 25 ms or lower is what you want to strive for.