In one embodiment, a method includes assigning a number of threads for user plane functions to a corresponding number of transmit queues for transmission of packets on a network interface, assigning additional threads exceeding the number of transmit queues to software transmission queues associated with the threads assigned to the transmit queues, identifying a load at each of the threads, dynamically updating assignment of the additional threads to the software transmission queues based on the load at the threads, and transmitting packets from the transmit queues for transmission on a network from a physical interface at a network device. An apparatus and logic are also disclosed herein.