Optimize for few args in EventEmitter.emit

lib/events.js

@@ -2,9 +2,10 @@ exports.EventEmitter = process.EventEmitter;
 
 
 process.EventEmitter.prototype.emit = function (type) {
-  if (type == 'error') {
+  // If there is no 'error' event listener then throw.
+  if (type === 'error') {
     if (!this._events || !this._events.error ||
-        (this._events.error instanceof Array && !this._events.error.length)) 
+        (this._events.error instanceof Array && !this._events.error.length))
     {
       if (arguments[1] instanceof Error) {
         throw arguments[1];
@@ -19,15 +20,23 @@ process.EventEmitter.prototype.emit = function (type) {
   if (!this._events[type]) return false;
 
   if (typeof this._events[type] == 'function') {
-    var args = Array.prototype.slice.call(arguments, 1);
-
-    this._events[type].apply(this, args);
+    if (arguments.length < 3) {
+      // fast case
+      this._events[type].call( this
+                             , arguments[1]
+                             , arguments[2]
+                             );
+    } else {
+      // slower
+      var args = Array.prototype.slice.call(arguments, 1);
+      this._events[type].apply(this, args);
+    }
     return true;
 
   } else if (this._events[type] instanceof Array) {
     var args = Array.prototype.slice.call(arguments, 1);
 
-    
+
     var listeners = this._events[type].slice(0);
     for (var i = 0, l = listeners.length; i < l; i++) {
       listeners[i].apply(this, args);