Group membership protocols are designed to achieve agreement among a set of replicated servers on a global service state, despite random message transmission delays, component failures, and server joins.This paper proposes a set of performance metrics for group membership protocols and investigates the performance characteristics of a suite of five asynchronous group membership protocols with regard to those metrics. After a brief description of the protocol suite, we propose a systematic procedure for determining the timeout delays used by the protocols, so as to achieve the best compromise between protocol stability and the speed with which failures are detected and joins are processed.The paper then discusses the measured performance of the membership protocols in an environment consisting of UNIX workstations interconnected by a 10 Megabit/sec Ethernet local area network.