LDAP directory server usage: effects on performance
If you are using an LDAP server to authenticate administrator and node passwords, there might be some performance impacts.
More processor resources are used when you are authenticating with a Lightweight Directory Access Protocol (LDAP) server instead of using local authentication. Tests in IBM® labs show that LDAP has about a 5% impact.
If you are using Secure Sockets Layer (SSL) sessions in combination with LDAP server authentication, the additional performance impact for sessions that transfer small amounts of data is negligible. For sessions that transfer large amounts of data, you can expect a significant performance impact because SSL must encrypt all of the data.