Existing techniques and tools have now been successfully used in research and development and have found several commercial applications as well. However, there is still a need for their extension in order to improve their efficiency, applicability and acceptance, as well as to cover domain specific needs. Especially methods dealing with complexity, and particulary with complexity in model specification, are of great importance. Further challenges lie in the area of queues with complex inputs, such as self-similar traffic, and techniques to compute resource demands of hierarchically structured software systems.
Simulation is still the most frequently used and the best accepted technique.
However, all applications suffer from insufficient performance of large simulation studies. Speed up of general simulation procedures by enhanced variance reduction techniques also need to be developed further. Additionally, requirements on existing and future techniques for easy usage of tool come from the users' side. Hiding mathematical details of performance evaluation methods makes these methods available in a variety of application areas. Making techniques available in tools, or packaging performance evaluation algorithms can essentially improve the acceptance and usability of these techniques.