1. A method for identifying sources of performance events in a processor, the method comprising the steps of: a) initializing event vectors in an instruction tracking structure of the processor; b) collecting information in the respective event vectors for every instruction flowing through the processor, wherein the information for such a vector includes selected execution history of the vector's associated instruction, some of the information being collected prior to completion of the instruction; and c) examining, responsive to completion of such an instruction, the history contained in the event vector for the instruction.