[ Thanks to Mike
Weber for this link. ]
“As you evaluate the sample data there are several
fields to pay close attention to. The first is the Cpu wa or
“amount of time the CPU has been waiting for I/O to
complete.” This at any sustained level will dramatically
decrease the speed or your mail server. Here is the wa from several
snapshots taken and you can see that running at the load that is
presented by the smtp-source is not sustainable”