Define the Division of Labour between Client and Server
Given our definition of client - server as the interaction between dispersed application logic components it must be noted that the execution location of these modules is very important to overall system performance, many application components will clearly execute more efficiently on either the client or the server.
For instance, logic components that may shared among client might be placed at the server for efficiency. If one server is processing the shared logic, the client will be freed to process another application component. Additionally, if many clients are active in the processing of non-centralized application logic, then the complete system become more scalable.