A method and apparatus for finding bottlenecks in software systems and other systems, given profiles that measure costs of the system. A simple profile interface, which is independent of the system and the method for measuring costs, provides operations for summarizing measurements in any profile that associates costs with paths. Then, an analyst uses one or more search tools which use the operations provided by the interface to generate summaries, where costly summaries represent bottlenecks. The set of operations provided by the interface not only support constructing summaries of cost measurements, but also support computing the overlap of summaries.