A virtualized platform includes a virtual switch connected to the virtual network interface cards (vNICs) for a group of virtual machines running the same application program that is associated with multiple software ports. A module in the virtualized platform monitors the virtual switch's receipt of a network packet that includes control information relating to the application program and its software ports. The module applies a load balancing algorithm to select a vNIC from the vNICs connected or connectable to the virtual switch, based on the rate of processing of previous network packets by each the vNICs (e.g., as measured by the size of a network packet queue). The module might also apply the load balancing algorithm to select a software port for the application. The module then causes the virtual switch to route the network packet to the selected vNIC and software port.