1. A method, comprising: determining, by a publish-subscribe system that runs on a computer system in a network, a consumption characteristic by which each of multiple subscribers consumes a subscription published by a publisher; identifying, by the publish-subscribe system, the subscribers whose consumption characteristics satisfy a specified similarity criterion; defining, by the publish-subscribe system, multiple subscription groups, each of which includes subscriptions of those of the subscribers whose consumption characteristics satisfy the specified similarity criterion; storing the subscriptions in multiple logical partitions of a storage system in the computer system, each of the logical partitions containing a separate non-overlapping subset of the subscriptions; and transmitting, by the publish-subscribe system, the subscriptions to the subscribers in accordance with the subscription groups.