diff --git a/CHANGELOG b/CHANGELOG
index ac7315b..28602c9 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,4 +1,6 @@
-* Reverse the definitions of Event#pointer(X|Y) and Event#pointer to prevent unnecessary computation. [#403 state:resolved] (Nick Stakenburg, Andrew Dupont).
+* Redefine Element#down in IE 6-7 to avoid extending all descendants when no selector is given. [#452 state:resolved] (eno, Andrew Dupont)
+
+* Reverse the definitions of Event#pointer(X|Y) and Event#pointer to prevent unnecessary computation. [#403 state:resolved] (Nick Stakenburg, Andrew Dupont)
 
 * Add first-class support for `mouseenter` and `mouseleave` events in non-IE browsers (IE supports them natively). [#350 state:resolved] (Nick Stakenburg, Andrew Dupont)
 
diff --git a/src/dom/dom.js b/src/dom/dom.js
index 0b15981..23ceb67 100644
--- a/src/dom/dom.js
+++ b/src/dom/dom.js
@@ -1323,6 +1323,28 @@ else if (Prototype.Browser.IE) {
       onchange:    v._getEv
     });
   })(Element._attributeTranslations.read.values);
+  
+  // We optimize Element#down for IE so that it does not call
+  // Element#descendants (and therefore extend all nodes).  
+  if (Prototype.BrowserFeatures.ElementExtensions) {
+    (function() {
+      function _descendants(element) {
+        var nodes = element.getElementsByTagName('*'), results = [];
+        for (var i = 0, node; node = nodes[i]; i++)
+          if (node.tagName !== "!") // Filter out comment nodes.
+            results.push(node);
+        return results;
+      }
+
+      Element.Methods.down = function(element, expression, index) {
+        element = $(element);
+        if (arguments.length == 1) return element.firstDescendant();
+        return Object.isNumber(expression) ? _descendants(element)[expression] :
+          Element.select(element, expression)[index || 0];
+      }    
+    })();
+  }
+  
 }
 
 else if (Prototype.Browser.Gecko && /rv:1\.8\.0/.test(navigator.userAgent)) {