Publish/Subscribe is the paradigm in which users express long-term interests («subscriptions») and some external agent (perhaps other users) «publishes» events (e.g., offers). The job of Publish/Subscribe software is to send events to the owners of subscriptions satisfied by those events. For example, a user subscription may consist of an interest in an airplane of a certain type, not to exceed a certain price. A published event may consist of an offer of an airplane with certain properties including price. A subscriptio- n closely resembles a trigger in that it is a long-lived conditional query associated with an action (usually, informing the subscriber). However, it is less general than a trigger so novel data structures and implementations may enable the creation of scalable, high performance publish-subscribe systems. This paper describes an attempt at the construction of such algorithm- s and its implementation. Using a combination of data structures, application-- specific caching policies, and application-specific query processing our system can handle 600 events per second on 6 million subscriptions consisting of conjunctions of (attribute, comparison operator, value) predicates.