All I don't know

package de.superclass 
{
    import flash.display.Sprite;
    import flash.events.Event;
    import flash.events.TimerEvent;
    import flash.utils.Timer;
    import flash.utils.getTimer;
 
    public final class LinkedListTest extends Sprite 
    {
        private var _abstractItemLinkedList : AbstractItem;
        private var _dataItemLinkedList : DataItem;
        private var _vector : Vector.<DataItem>;
 
        public function LinkedListTest()
        {
            loaderInfo.addEventListener( Event.COMPLETE, onLoaderInfoComplete );
        }
 
        private function onLoaderInfoComplete( event : Event ) : void 
        {
            createData( );
 
            var timer : Timer = new Timer( 3000, 1 );
                timer.addEventListener( TimerEvent.TIMER_COMPLETE, onTimerComplete );
                timer.start();
        }
 
        private function onTimerComplete(event : TimerEvent) : void 
        {
            runTest( );
        }
 
        private function createData() : void 
        {
            var vector : Vector.<DataItem> = _vector = new Vector.<DataItem>();
            for ( var i : int = 0; i < 5000000; i++ )
            {
                var dataItem : DataItem = new DataItem();
                    dataItem.index = i;
 
                vector.push( dataItem );
 
                var abstractItem : AbstractItem = new AbstractItem();
                    abstractItem.data = dataItem;
 
                if ( i == 0 )
                {
                    _dataItemLinkedList = dataItem;
                    _abstractItemLinkedList = abstractItem;
                }
                else
                {
                    previousDataItem.next = dataItem;
                    previousAbstractItem.next = abstractItem;
                }
 
                var previousDataItem : DataItem = dataItem;
                var previousAbstractItem : AbstractItem = abstractItem;
            }
        }
 
        private function runTest() : void 
        {
            var dataItem : DataItem;
            var startTime : int;
 
            var vector : Vector.<DataItem> = _vector;
            var c : int = vector.length;
 
            startTime = getTimer();
            for ( var i : int = 0; i < c; i++ )
            {
                dataItem = vector[ i ];
                dataItem.index = dataItem.index;
            }
 
            var durationVector : int = getTimer() - startTime;
 
            startTime = getTimer();
            dataItem = _dataItemLinkedList;
            while ( dataItem )
            {
                dataItem.index = dataItem.index;
                dataItem = dataItem.next;
            }
 
            var durationDataItemLinkedList : int = getTimer() - startTime;
 
            startTime = getTimer( );
            var abstractItem : AbstractItem = _abstractItemLinkedList;
            while ( abstractItem )
            {
                dataItem = abstractItem.data;
                dataItem.index = dataItem.index;
                abstractItem = abstractItem.next;
            }
 
            var durationAbstractItemLinkedList : int = getTimer() - startTime;
 
            startTime = getTimer( );
            abstractItem = _abstractItemLinkedList;
            while ( abstractItem )
            {
                dataItem = DataItem( abstractItem.data );
                dataItem.index = dataItem.index;
                abstractItem = abstractItem.next;
            }
 
            var durationAbstractItemLinkedListWithCast : int = getTimer() - startTime;
 
            startTime = getTimer( );
            abstractItem = _abstractItemLinkedList;
            while ( abstractItem )
            {
                dataItem = abstractItem.data as DataItem;
                dataItem.index = dataItem.index;
                abstractItem = abstractItem.next;
            }
 
            var durationAbstractItemLinkedListWithAs : int = getTimer() - startTime;
 
            trace( "Durations:" );
            trace( "Vector", durationVector );
            trace( "DataItem LinkedList", durationDataItemLinkedList );
            trace( "AbstractItem LinkedList", durationAbstractItemLinkedList );
            trace( "AbstractItemLinkedList Using Cast", durationAbstractItemLinkedListWithCast );
            trace( "AbstractItemLinkedList Using As", durationAbstractItemLinkedListWithAs );
        }
    }
 
}
 
class AbstractItem
{
    public var data : *;
    public var next : AbstractItem;
}
 
class DataItem
{
    public var index : int;
    public var next : DataItem;
}