/bind numpad4 "netgraph 1"The core of the whole system. /bind attaches a command to a key; the command goes in quotes. Anything you can type into chat, and every internal engine command, can be bound this way.
netgraph 1 shows framerate, latency and packet loss; netgraph 0 hides it again. Binding both to one key pair makes it easy to check whether a lag spike is you or the server.
/bind numpad1 "netgraph 1"
/bind numpad0 "netgraph 0"