The following was written by, and for, FreeBSD users who also happen to work with MacOS X. They’ll be quite familiar with the below to tune tcp space for speed and efficiency:

/usr/sbin/sysctl -w net.inet.tcp.sendspace=65536 > /dev/null /usr/sbin/sysctl -w net.inet.tcp.recvspace=65536 > /dev/null /usr/sbin/sysctl -w kern.ipc.maxsockbuf=262144 > /dev/null /usr/sbin/sysctl -w net.inet.tcp.delayed_ack=0 > /dev/null /usr/sbin/sysctl -w net.inet.udp.recvspace=41600 > /dev/null /usr/sbin/sysctl -w net.inet.tcp.v6mssdflt=1020 > /dev/null

The below sets the MTU for my AirPort card to 1942, as it should be™.

/sbin/ifconfig en1 mtu 1492 > /dev/null

I place these in /opt/local/etc/rc.d/systune.sh , which is called via DarwinPorts’ Startup.

To see all of your sysctl controllable/readable variables, you can use sysctl -a , but please be wary that if you change things you don’t understand, you’ll likely make things unusable until you reboot!