added updated throttling

README.md

@@ -16,7 +16,7 @@ See the [jquery.matchHeight.js demo](http://brm.io/jquery-match-height-demo).
 ### Features
 
 - row aware, handles floating elements
-- responsive, automatically updates on window resize
+- responsive, automatically updates on window resize (can be throttled for performance)
 - handles mixed `padding`, `margin`, `border` values (even if every element has them different)
 - accounts for `box-sizing`
 - handles images and other media (updates automatically after loading)
@@ -103,6 +103,12 @@ If you need to manually trigger an update of all currently set equal heights gro
 
 Use the apply function directly if you wish to avoid the automatic update functionality.
 
+	$.fn.matchHeight._throttle = 80;
+
+By default, the `_update` method is throttled to execute at a maximum rate of once every `80ms`.
+Decreasing the above `_throttle` property will update your layout quicker, appearing smoother during resize, at the expense of performance.
+If you experience lagging or freezing during resize, you should increase the `_throttle` property.
+
 ### Why not use CSS?
 
 Making robust, responsive equal height columns for _arbitrary content_ is [difficult or impossible](http://filamentgroup.com/lab/setting_equal_heights_with_jquery/) to do with CSS alone (at least without hacks or trickery, in a backwards compatible way).

jquery.matchHeight.js

@@ -141,11 +141,12 @@
     */
 
     $.fn.matchHeight._groups = [];
+    $.fn.matchHeight._throttle = 80;
 
-    var previousResizeWidth = -1;
+    var previousResizeWidth = -1,
+        updateTimeout = -1;
 
     $.fn.matchHeight._update = function(event) {
-
         // prevent update if fired from a resize event 
         // where the viewport width hasn't actually changed
         // fixes an event looping bug in IE8
@@ -156,9 +157,18 @@
             previousResizeWidth = windowWidth;
         }
 
-        $.each($.fn.matchHeight._groups, function() {
-            $.fn.matchHeight._apply(this.elements, this.byRow);
-        });
+        // throttle updates
+        if (updateTimeout === -1) {
+            updateTimeout = setTimeout(function() {
+
+                $.each($.fn.matchHeight._groups, function() {
+                    $.fn.matchHeight._apply(this.elements, this.byRow);
+                });
+
+                updateTimeout = -1;
+
+            }, $.fn.matchHeight._throttle);
+        }
     };
 
     /*