An apparatus includes one or more ports for connecting to a communication network, processing circuitry and a message aggregation circuit (MAC). The processing circuitry is configured to communicate messages over the communication network via the one or more ports. The MAC is configured to receive messages, which originate in one or more source processes and are destined to one or more destination processes, to aggregate two or more of the messages that share a common destination into an aggregated message, and to send the aggregated message using the processing circuitry over the communication network.