diff --git a/lib/child_process.js b/lib/child_process.js
index 4ed5a544a0..5a90442261 100644
--- a/lib/child_process.js
+++ b/lib/child_process.js
@@ -76,10 +76,10 @@ ChildProcess.prototype.spawn = function (path, args, env) {
   args = args || [];
   env = env || process.env;
   var envPairs = [];
-  for (var key in env) {
-    if (env.hasOwnProperty(key)) {
-      envPairs.push(key + "=" + env[key]);
-    }
+  var keys = Object.keys(env);
+  for (var index = 0, keysLength = keys.length; index < keysLength; index++) {
+    var key = keys[index];
+    envPairs.push(key + "=" + env[key]);
   }
 
   var fds = this._internal.spawn(path, args, envPairs);
diff --git a/lib/dns.js b/lib/dns.js
index 6794ef426f..9bfca4752e 100644
--- a/lib/dns.js
+++ b/lib/dns.js
@@ -8,7 +8,9 @@ var activeWatchers = {};
 var timer = new process.Timer();
 
 timer.callback = function () {
-  for (var socket in activeWatchers) {
+  var sockets = Object.keys(activeWatchers);
+  for (var i = 0, l = sockets.length; i < l; i++) {
+    var socket = sockets[i];
     var s = parseInt(socket);
     channel.processFD( watchers[socket].read  ? s : dns.SOCKET_BAD
                      , watchers[socket].write ? s : dns.SOCKET_BAD
@@ -21,13 +23,16 @@ timer.callback = function () {
 function updateTimer() {
   timer.stop();
 
-  for (var socket in activeWatchers) { // if !empty(activeWatchers)
-    var max = 20000;
-    var timeout = channel.timeout(max);
-
-    timer.start(timeout, 0);
+  // Were just checking to see if activeWatchers is empty or not
+  for (var socket in activeWatchers) {
+    if (activeWatchers.hasOwnProperty(socket)) {
+      var max = 20000;
+      var timeout = channel.timeout(max);
 
-    return;
+      timer.start(timeout, 0);
+      // Short circuit the loop on first find.
+      return;
+    }
   }
 }
 
diff --git a/lib/fs.js b/lib/fs.js
index 4b2a4d120a..c3ab698e63 100644
--- a/lib/fs.js
+++ b/lib/fs.js
@@ -490,7 +490,13 @@ var FileReadStream = fs.FileReadStream = function(path, options) {
   this.bufferSize = 4 * 1024;
 
   options = options || {};
-  for (var i in options) this[i] = options[i];
+
+  // Mixin options into this
+  var keys = Object.keys(options);
+  for (var index = 0, length = keys.length; index < length; index++) {
+    var key = keys[index];
+    this[key] = options[key];
+  }
 
   var self = this;
 
@@ -621,7 +627,13 @@ var FileWriteStream = fs.FileWriteStream = function(path, options) {
   this.mode = 0666;
 
   options = options || {};
-  for (var i in options) this[i] = options[i];
+
+  // Mixin options into this
+  var keys = Object.keys(options);
+  for (var index = 0, length = keys.length; index < length; index++) {
+    var key = keys[index];
+    this[key] = options[key];
+  }
 
   this.busy = false;
   this._queue = [];
diff --git a/lib/http.js b/lib/http.js
index 12130b68b6..717085396d 100644
--- a/lib/http.js
+++ b/lib/http.js
@@ -267,29 +267,34 @@ OutgoingMessage.prototype.sendHeaderLines = function (firstLine, headers) {
   // in the case of response it is: "HTTP/1.1 200 OK\r\n"
   var messageHeader = firstLine;
   var field, value;
-  for (var i in headers) {
-    if (headers[i] instanceof Array) {
-      field = headers[i][0];
-      value = headers[i][1];
-    } else {
-      if (!headers.hasOwnProperty(i)) continue;
-      field = i;
-      value = headers[i];
-    }
 
-    messageHeader += field + ": " + value + CRLF;
+  if (headers) {
+    var keys = Object.keys(headers);
+    var isArray = (headers instanceof Array);
+    for (var i = 0, l = keys.length; i < l; i++) {
+      var key = keys[i];
+      if (isArray) {
+        field = headers[key][0];
+        value = headers[key][1];
+      } else {
+        field = key;
+        value = headers[key];
+      }
+
+      messageHeader += field + ": " + value + CRLF;
 
-    if (connectionExpression.test(field)) {
-      sentConnectionHeader = true;
-      if (closeExpression.test(value)) this.closeOnFinish = true;
+      if (connectionExpression.test(field)) {
+        sentConnectionHeader = true;
+        if (closeExpression.test(value)) this.closeOnFinish = true;
 
-    } else if (transferEncodingExpression.test(field)) {
-      sentTransferEncodingHeader = true;
-      if (chunkExpression.test(value)) this.chunkedEncoding = true;
+      } else if (transferEncodingExpression.test(field)) {
+        sentTransferEncodingHeader = true;
+        if (chunkExpression.test(value)) this.chunkedEncoding = true;
 
-    } else if (contentLengthExpression.test(field)) {
-      sentContentLengthHeader = true;
+      } else if (contentLengthExpression.test(field)) {
+        sentContentLengthHeader = true;
 
+      }
     }
   }
 
@@ -696,10 +701,21 @@ exports.cat = function (url, encoding_, headers_) {
   var url = require("url").parse(url);
   
   var hasHost = false;
-  for (var i in headers) {
-    if (i.toLowerCase() === "host") {
-      hasHost = true;
-      break;
+  if (headers instanceof Array) {
+    for (var i = 0, l = headers.length; i < l; i++) {
+      if (headers[i][0].toLowerCase() === 'host') {
+        hasHost = true;
+        break;
+      }
+    }
+  } else if (typeof headers === "Object") {
+    var keys = Object.keys(headers);
+    for (var i = 0, l = keys.length; i < l; i++) {
+      var key = keys[i];
+      if (key.toLowerCase() == 'host') {
+        hasHost = true;
+        break;
+      }
     }
   }
   if (!hasHost) headers["Host"] = url.hostname;
diff --git a/lib/ini.js b/lib/ini.js
index 3a59457c60..ad309b719a 100644
--- a/lib/ini.js
+++ b/lib/ini.js
@@ -42,24 +42,35 @@ function safe (val) {
   return (val+"").replace(/[\n\r]+/g, " ");
 }
 
+// ForEaches over an object. The only thing faster is to inline this function.
+function objectEach(obj, fn, thisObj) {
+  var keys, key, i, length;
+  keys = Object.keys(obj);
+  length = keys.length;
+  for (i = 0; i < length; i++) {
+    key = keys[i];
+    fn.call(thisObj, obj[key], key, obj);
+  }
+}
+
 exports.stringify = function (obj) {
   // if the obj has a "-" section, then do that first.
-  var ini = "";
+  var ini = [];
   if ("-" in obj) {
-    for (var key in obj["-"]) {
-      ini += safe(key)+" = "+safe(obj["-"][key])+"\n";
-    }
+    objectEach(obj["-"], function (value, key) {
+      ini[ini.length] = safe(key) + " = " + safe(value) + "\n";
+    });
   }
-  for (var section in obj) if (section !== "-") {
-    ini += "[" + safe(section) + "]\n";
-    for (var key in obj[section]) {
-
-      ini += safe(key) + ((obj[section][key] === true)
+  objectEach(obj, function (section, name) {
+    if (name === "-") return;
+    ini[ini.length] = "[" + safe(name) + "]\n";
+    objectEach(section, function (value, key) {
+      ini[ini.length] = safe(key) + ((value === true)
         ? "\n"
-        : " = "+safe(obj[section][key])+"\n");
-    }
-  }
-  return ini;
+        : " = "+safe(value)+"\n");
+    });
+  });
+  return ini.join("");
 };
 
 exports.encode = exports.stringify;
diff --git a/lib/querystring.js b/lib/querystring.js
index 5220b53ae9..83e0a0f85e 100644
--- a/lib/querystring.js
+++ b/lib/querystring.js
@@ -55,9 +55,11 @@ QueryString.stringify = function (obj, sep, eq, name) {
   var s = [];
   var begin = name ? name + '[' : '';
   var end = name ? ']' : '';
-  for (var i in obj) if (obj.hasOwnProperty(i)) {
-    var n = begin + i + end;
-    s.push(QueryString.stringify(obj[i], sep, eq, n));
+  var keys = Object.keys(obj);
+  for (var i = 0, l = keys.length; i < l; i++) {
+    var key = keys[i];
+    var n = begin + key + end;
+    s.push(QueryString.stringify(obj[key], sep, eq, n));
   }
 
   stack.pop();
@@ -138,10 +140,14 @@ function mergeParams (params, addition) {
 };
 
 // Merge two *objects* together. If this is called, we've already ruled
-// out the simple cases, and need to do the for-in business.
+// out the simple cases, and need to do a loop.
 function mergeObjects (params, addition) {
-  for (var i in addition) if (i && addition.hasOwnProperty(i)) {
-    params[i] = mergeParams(params[i], addition[i]);
+  var keys = Object.keys(addition);
+  for (var i = 0, l = keys.length; i < l; i++) {
+    var key = keys[i];
+    if (key) {
+      params[key] = mergeParams(params[key], addition[key]);
+    }
   }
   return params;
 };
diff --git a/lib/url.js b/lib/url.js
index e6f2d71ebe..c4b534a5d5 100644
--- a/lib/url.js
+++ b/lib/url.js
@@ -56,7 +56,11 @@ function urlParse (url, parseQueryString) {
 
     // pull out the auth and port.
     var p = parseHost(out.host);
-    for (var i in p) out[i] = p[i];
+    var keys = Object.keys(p);
+    for (var i = 0, l = keys.length; i < l; i++) {
+      var key = keys[i];
+      out[key] = p[key];
+    }
     // we've indicated that there is a hostname, so even if it's empty, it has to be present.
     out.hostname = out.hostname || "";
   }
diff --git a/src/node.js b/src/node.js
index 675e3bc048..eb703d93c7 100644
--- a/src/node.js
+++ b/src/node.js
@@ -462,7 +462,9 @@ function findModulePath (id, dirs, callback) {
   ];
 
   var ext;
-  for (ext in extensionCache) {
+  var extensions = Object.keys(extensionCache);
+  for (var i = 0, l = extensions.length; i < l; i++) {
+    var ext = extensions[i];
     locations.push(path.join(dir, id + ext));
     locations.push(path.join(dir, id, 'index' + ext));
   }
@@ -504,7 +506,9 @@ function resolveModulePath(request, parent) {
     debug("RELATIVE: requested:" + request + " set ID to: "+id+" from "+parent.id);
 
     var exts = ['js', 'node'], ext;
-    for (ext in extensionCache) {
+    var extensions = Object.keys(extensionCache);
+    for (var i = 0, l = extensions.length; i < l; i++) {
+      var ext = extensions[i];
       exts.push(ext.slice(1));
     }