1. A method for performing event processing comprising: evaluating an event stream; for each event of a plurality of events in the event stream, mapping the event to a mapped target instance of a plurality of target instances and adding the event to at least one queue of a plurality of queues each corresponding to a thread of a plurality of threads, each thread having at least one target instance of the plurality of target instances assigned thereto; evaluating loading of the plurality of queues; in response to the evaluation, reassigning a selected target instance of the one or more target instances associated with a first thread of the plurality of threads to a second thread of the plurality of threads; and processing events in the queue corresponding to the first thread by: evaluating the mapped target instance for the event; and if the mapped target instance corresponds to the selected target instance, adding the event to the queue corresponding to the second thread.