quick-test node udp latency: start server.js, then start the client.js

client.js

var udp = require('dgram');
var s = udp.createSocket('udp4');
s.bind(27016, '127.0.0.1');

var t;

s.on('message', function(data, remote) {
        var req = data.toString();

        if (req == 'go-ahead') {
                var response = new Buffer('done');

                s.send(response, 0, response.length, remote.port, remote.address, function () {
                        s.close();
                });
        }
});


var readyMessage = new Buffer('ready');
s.send(readyMessage, 0, readyMessage.length, 27015, '127.0.0.1') ;

server.js

var udp = require('dgram');
var s = udp.createSocket('udp4');
s.bind(27015, '127.0.0.1');

var t;

s.on('message', function(data, remote) {
        var req = data.toString();
        console.log(req);
        if (req == 'ready') {
                var response = new Buffer('go-ahead');

                t = new Date().getTime();
                console.log(t);
                s.send(response, 0, response.length, remote.port, remote.address);
        }
        else if (req == 'done') {
                console.log(new Date().getTime());
                console.log(new Date().getTime() - t);
                s.close();
        }
});