[flexcoders] how to fix poor performance in this example (AdvancedDataGrid and Binding)

[Pan Troglodytes]

I have the following example that is a very simplified form of what I need
to do in my much larger program.  The goal is to have a mouseover on a grid
item set a variable in the data object.  In the real program, this fires off
some other code which makes that item visible and the others hidden, etc.
But here, I'm just trying the first part.

*TestObject.as:*
package
{
  public class TestObject
  {
    [Bindable] public var label:String;
    [Bindable] public var highlighted:Boolean;
  }
}

*GenericTest.mxml:
*<?xml version="1.0" encoding="utf-8"?>
<Application
  xmlns="http://www.adobe.com/2006/mxml";
  creationComplete="cc()"
  layout="horizontal"
  >
  <Script>
    <![CDATA[
      import mx.events.ListEvent;
      import mx.collections.ArrayCollection;
      [Bindable] public var d:ArrayCollection = new ArrayCollection([]);

      private const ITEM_COUNT:int = 15;

      private function cc():void
      {
        for (var i:int = 0; i < ITEM_COUNT; i++)
        {
          var item:TestObject = new TestObject;
          item.label = "Item " + i;
          d.addItem(item);
        }
      }

      private function listRollover(e:ListEvent):void
      {
        for each (var item:TestObject in d)
          item.highlighted = list.isItemHighlighted(item);
      }

      private function getColStyle(data:Object,
column:AdvancedDataGridColumn):Object
      {
        return { fontWeight:(list.isItemHighlighted(data) ? "bold" :
"normal") }
      }

      private function getColStyle2(data:Object,
column:AdvancedDataGridColumn):Object
      {
        return { fontWeight:(list2.isItemHighlighted(data) ? "bold" :
"normal") }
      }

    ]]>
  </Script>
  <AdvancedDataGrid id="list" dataProvider="{d}" height="100%"
itemRollOver="listRollover(event)">
    <columns>
      <AdvancedDataGridColumn styleFunction="getColStyle"
dataField="label"/>
    </columns>
  </AdvancedDataGrid>
  <AdvancedDataGrid id="list2" dataProvider="{d}" height="100%">
    <columns>
      <AdvancedDataGridColumn styleFunction="getColStyle2"
dataField="label"/>
    </columns>
  </AdvancedDataGrid>
</Application>

To see the problem, run your mouse up and down the list on the left and the
list on the right.  If you get the same results I do with SDK 3.0.2 and
player 10,0,12,36 (FF 3.0.6 or IE 7), you'll see that the list on the right
tracks very smoothly but the one on the left is choppy.  The only difference
between the two is that the one on the left has a rollOver handler that sets
a Bindable variable in the data object.

If you comment out the [Bindable] on TestObject's highlighted variable, the
choppiness goes away.  So it's something to do with all the binding glue
being fired behind the scenes.  Is there some good way to work around this
while still being able to use binding in this way?

-- 
Jason