gistfile1.js

var fact = function(n) { if (n === 0) return 1; return n * fact(n - 1); };

var start = process.hrtime();
fact(150);
var diff = process.hrtime(start);

console.log('fact(150) took %d nanoseconds', diff[0] * 1e9 + diff[1]);

var child_process = require('child_process');
var start = process.hrtime();
child_process.exec('ls', function(err, stdout, stderr) {
  // do nothing
});
var diff = process.hrtime(start);

console.log('exec took %d nanoseconds', diff[0] * 1e9 + diff[1]);