The explosion of content in distributed information retrieval (IR) systems requires new mechanisms in order to attain timely and accurate retrieval of unstructured text. Collection selection and partial collection replication with replica selection are two such mechanisms that enable IR systems to search a small percentage of data and thus improve performance and scalability. To maintain effectiveness simultaneously, IR systems must be configured carefully, and consider workload locality, possible collection organizationscollection organization, and any interaction that results. This work builds on previous results which have focused on maintaining effectiveness. We propose IR system architectures with collection selection and partial replication based on collection organization and query locality characteristics which maintain accuracy and achieve high performance. We compare configurations using a validated simulator that partition data and replicate data, and their sensitivities to ...