Recent versions of CoffeeScript greatly improved compilation of fat arrows.

This:

    x = (a) =>
      y = (b) =>
        z = (c) =>
          @q * a * b * c

Becomes this:

    var x,
      _this = this;

    x = function(a) {
      var y;
      return y = function(b) {
        var z;
        return z = function(c) {
          return _this.q * a * b * c;
        };
      };
    };

Instead of this:

    var x;
    var __bind = function(fn, me){ return function(){ return fn.apply(me, arguments); }; };
    x = __bind(function(a) {
      var y;
      return y = __bind(function(b) {
        var z;
        return z = __bind(function(c) {
          return this.q * a * b * c;
        }, this);
      }, this);
    }, this);

Taze is (presumably) talking about the inherent inefficiency of all those functions having prototypes.

(You know, the thing that was mentioned in the linked article?)