A frequent question asked is "WebSphere Portal ships with a lot of applications. But, I don't need all of those applications. Each of the applications takes time to start when the Portal server starts, and, consumes memory/CPU during runtime. How do I know which applications are required for the Portal server to function, and which are optional and can be safely disabled?".
For Portal 6.1.x, please see the following Technote: "How to disable unused applications in WebSphere Portal V6.1.x"