The prediction of the performance at early stages of the development of large software systems has turned out to be a very challenging task. There are already several techniques and methodologies available, each having its own advantages and limitations. This paper discusses using different techniques, one analytical and one simulative, for performance analysis in one case study and compares the results and thereby validates the accuracy of each technique. This paper is a proof of concept for a new modeling technique called FMC-QE (Fundamental Modeling Concepts for Quantitative Evaluation) and the simulation framework Perfact. Perfact simulates the performance of early prototypes in the real application environment. The examined case study is a Web service application run in the SAP environment. It was modeled with use of FMC-QE and simulated with the Perfact framework.