Web services have many important advantages. But their great drawback, the invocation overhead, has not been a research focus. So far, only invocations of simple Web services were considered. But Web service composition may create additional performance problems. Our measurements demonstrate that Web service composition may reduce the maximal load of a system drastically. The reduction quotient increases quasi-exponentially with the number of service compositions. We call that phenomenon "service congestion" since it is not due to the combined payload of the composed services. Such detrimental performance effects can not be tolerated in many areas. For that reason, we propose an optimized service composition architecture as a solution. This service component architecture uses service connectors on top of standard Web service middleware. It optimizes automatically the local invocation of services with a Lookup & Service bus. The result is that no service congestion occurs since local service invocations have the cost of local calls.