The conventional methodology for system performance measurement, which relies primarily on throughput-sen sitive benchmarks and throughput metrics, has major limitations when analyzing the behavior and perfor mance of interactive workloads. The increasingly inter active character of personal computing demands new ways of measuring and analyzing system performance. In this paper, we present a combination of measurement techniques and benchmark methodologies that address these problems. We introduce several simple methods for making direct and precise measurements of event handling latency in the context of a realistic interactive application. We analyze how results from such measure ments can be used to understand the detailed behavior of latency-critical events. We demonstrate our techniques in an analysis of the performance of two releases of Windows NT and Windows 95. Our experience indi cates that latency can be measured for a class of interac tive workloads, providing a substantial improvement in the accuracy and detail of performance information over measurements based strictly on throughput.