Is it required to extend or newly implement a software? Which type of server or operation system is reasonable? What happens, if hundreds of users access at the same time? In software development, enterprises face problems like these. If a "software" grows, errors with enormous consequences may occur rapidly. By means of domain-specific modeling (DSM) and component-based development (CBD), a high degree of automation and good software quality are achieved. However, a system is lacking, by means of which reliable performance prognoses can be made when designing the architecture. Software architecture plays a decisive role for the time behavior in particular of operational information systems. Errors in the software architecture mostly cannot be compensated by the hardware. Named after the renaissance architect, "Palladio" is a model-based performance prognosis approach for software architectures. It comprises an eclipse-based work environment to early and rapidly make design decisions at the architecture level. Palladio supports the investigation of performance aspects by "what-if-analysis". All possible situations are considered and the risk of bottlenecks due to hardly revisble decisions is reduced. Implementation is not required, as the process works on the architecture design. Developers can study and evaluate impacts on the performance of changes of the software design, user profile, or hardware at the model level. Moreover, Palladio is model-driven and allows for the generation of code skeletons from models, such as the automatic generation of enterprise Java implementations.