Because memory is a limited resource, it is important to use it properly. In the case of a database application, it is important to increase broker parameters first because the payback extends across all users and the system as a whole. This fact is demonstrated with the previous database buffer hit percentage example that shows how a small change on the broker side can dramatically affect the entire system. The size of the change on the broker is usually smaller relative to any self-service client changes you might make.
For example, a 1000 buffer increase for the –B parameter on the broker of an 8KB-block-size database costs you 8MB of RAM, and an 80KB increase on the –mmax parameter for a 100-user system costs the same 8MB of RAM. In the majority of cases, a buffer increase has a greater overall impact than the client change. This simple example demonstrates that you should always tune your broker parameters first. Once that is complete and you still have RAM to allocate, you can then focus on the self-service client parameters.