Devices, systems, and methods of improving transport protocol performance in a multi-path environment are disclosed. One network device comprises a transport-layer proxy; and a multi-path traffic distributor coupled to the transport-layer proxy. The transport-layer proxy is configured to receive packets, each associated with a transport-layer connection, from a transport-layer endpoint. The proxy is further configured to deliver at least a portion of the received packets to the multi-path traffic distributor. The multi-path traffic distributor is configured to: assign each of the delivered packets to one of a plurality of data flows, and to transmit each of the delivered packets on an outbound path associated with the assigned data flow.