TCP

The Transport Control Protocol is a connection-oriented mechanism that is part of the IP protocol suite.

TCP Tuning in for Gigabit Ethernet

(from notes regarding this guide)

$ cat /etc/sysctl.conf
net.inet.tcp.mssdflt=1440
kern.ipc.maxsockbuf=800000
net.inet.tcp.sendspace=400000
net.inet.tcp.recvspace=400000

All of the above are applicable at runtime with sudo sysctl -w.