Methods and apparatus, including computer program products, implementing and using techniques for identifying currently dominant events in a computer system. Events in the computer system are monitored. A subset of the monitored events is selected. Priorities are assigned to the events in the subset of monitored events. The priorities are generated through applying a mathematical formula to each event in the subset of events, which mathematical formula discounts old events relative to recent events. A first set of priorities is stored in a first priority queue. The first set of priorities identifies the currently dominant events in the subset of monitored events.