Communication apparatus includes multiple interfaces connected to a packet data network. A memory is coupled to the interfaces and configured as a buffer to contain packets received through ingress interfaces while awaiting transmission to the network via respective egress interfaces. Packet processing logic is configured, upon receipt of a multicast packet through an ingress interface, to identify a number of the egress interfaces through which respective copies of the multicast packet are to be transmitted, to allocate a space in the buffer for storage of a single copy of the multicast packet, to replicate and transmit multiple copies of the stored copy of the multicast packet through the egress interfaces, to maintain a count of the replicated copies that have been transmitted, and when the count reaches the identified number, to release the allocated space in the buffer.