monomorphism.js

var print = typeof print === 'function' ? print : console.log.bind(console);

function X() {
}

X.prototype.dispatch = function (obj) {
  this[obj.type](obj);
};

var DEGREE = 20;

var objs = [];

for (var i = 0; i < DEGREE; i++) {
  var o = { type: eval(JSON.stringify("t" + i)) };  // poor mans intern
  objs.push(o);
  X.prototype[o.type] = function (o) { };
}

function measure(objs) {
  var x = new X();
  var start = Date.now();
  for (var i = 0; i < 100000; i++) {
    for (var j = 0; j < objs.length; j++) {
      x.dispatch(objs[j]);
    }
  }
  var end = Date.now();
  print(end - start);
}

measure(objs);