Quorum systems are well-known tools that improve the performance and the availability of distributed systems. In this paper we explore their use as a means to achieve low response time for network services that are replicated and accessed over computing grids. To that end, we propose both a quorum construction and a quorum-based state-machine replication algorithm that tolerates crash failures in a partially synchronous model. We show through the evaluation of a real implementation that although simple, this quorum construction and replication algorithm exhibits a response time 20% lower than that of a regular active replication algorithm in appropriate conditions.