1. A method for adjusting a maximum transmission unit of a plurality of network packets, the method comprising: establishing, by an intermediary deployed between a client and a server, a connection between the client and the server, the intermediary performing encryption of a plurality of network packets for the connection traversing the intermediary; receiving, by the intermediary, a plurality of network packets via the connection from the server destined for the client, the plurality of network packets transmitted to the server in accordance with a maximum transmission unit; determining, by the intermediary, an encryption overhead for encryption performed by the intermediary on each of the plurality of network packets; adjusting, by the intermediary, the maximum transmission unit by at least a size of an encryption overhead of a network packet of the plurality of network packets of the connection having a largest encryption overhead; and transmitting, by the intermediary, the plurality of network packets to the client via the connection in accordance with the adjusted maximum transmission unit.