https://github.com/joyent/node/issues/6715 (see http://neversaw.us/2013/09/04/on-the-performance-of-closures-in-v8/)

deps_getset.js

var z = 1;

var add = (function add__ ($$) {
	return function add (x, y) {
		var __ = $$;
		//__.z = -__.z;
		return x + y + __.z;
	};
}) ({
	get z () { return z; },
	set z (__) { z = __; },
});

var f = (function f__ ($$) {
	return function f () {
		var __ = $$;
		var add = __.add;
		var sum = 0;
		for (var i = 0; i < 10000; i++) {
			sum = add(sum, i);
			//sum = __.add(sum, i); // takes 100x as long !!!!!
		}
		//if (sum != 49995000) throw "argh";
	};
}) ({
	get add () { return add; },
});

function measure(f) {
  var start = new Date().valueOf();
  for (var i = 0; i < 100000; i++) {
  	// invoke f() with f_this as "this" -- thus exposing the add() method
    f();
  }
  var end = new Date().valueOf();
  if (typeof console !== "undefined") {
	  console.log(end - start);
  } else {
	  print(end - start);
  }
}

measure(f); // (10s on node, 2.6s on node-webkit, 1.6s on Chrome, 1.7s on d8)

deps_pewpew.js

var z = 1;

var add = (function add__ ($$) {
	var a = function add (x, y) {
		var __ = this;
		//__.z = -__.z;
		return x + y + __.z;
	};

	a.__ = $$;
	$$.__ = a;

	return a;
}) ({
	get z () { return z; },
	set z (__) { z = __; },
});

var f = (function f__ ($$) {
	var b = function f () {
		var __ = this;
		var lax;
		var add = __.add;
		var sum = 0;
		for (var i = 0; i < 10000; i++) {
			sum = add.__.__(sum, i);
			//sum = (lax = __.add)(sum, i); // takes 100x as long !!!!!
		}
		//if (sum != 49995000) throw "argh";
	};

	b.__ = $$;
	$$.__ = b;

	return b;
}) ({
	get add () { return add; },
});

function measure(f) {
  var start = new Date().valueOf();
  for (var i = 0; i < 100000; i++) {
  	// invoke f() with f_this as "this" -- thus exposing the add() method
    f.__.__();
  }
  var end = new Date().valueOf();
  if (typeof console !== "undefined") {
	  console.log(end - start);
  } else {
	  print(end - start);
  }
}

measure(f); // (1.6s on node, 1.6s on node-webkit, 2.4s on Chrome, 1.7s on d8)

deps_value.js

var z = 1;

var add = (function add__ ($$) {
	return function add (x, y) {
		var __ = $$;
		//__.z = -__.z;
		return x + y + __.z;
	};
}) ({
	z: z,
});

var f = (function f__ ($$) {
	return function f () {
		var __ = $$;
		var add = __.add;
		var sum = 0;
		for (var i = 0; i < 10000; i++) {
			sum = add(sum, i);
			//sum = __.add(sum, i); // takes 100x as long !!!!!
		}
		//if (sum != 49995000) throw "argh";
	};
}) ({
	add: add,
});

function measure(f) {
  var start = new Date().valueOf();
  for (var i = 0; i < 100000; i++) {
  	// invoke f() with f_this as "this" -- thus exposing the add() method
    f();
  }
  var end = new Date().valueOf();
  if (typeof console !== "undefined") {
	  console.log(end - start);
  } else {
	  print(end - start);
  }
}

measure(f); // (6.9s on node, 1.6s on node-webkit, 1.6s on Chrome, 1.7s on d8)

deps_vanilla.js

var z = 1;

function add(x, y) {
  return x + y + z;
}

function f() {
  var sum = 0;
  for (var i = 0; i < 10000; i++) {
    sum = add(sum, i);
  }
  //if (sum != 49995000) throw "argh";
}

function measure(f) {
  var start = new Date().valueOf();
  for (var i = 0; i < 100000; i++) {
    f();
  }
  var end = new Date().valueOf();
  if (typeof console !== "undefined") {
	  console.log(end - start);
  } else {
	  print(end - start);
  }
}

measure(f);