Benchmark of several variants of type casting in AS3

CastingSpeed.as

package
{
    import flash.display.*;
    import flash.text.*;
    import flash.utils.*;

    public class CastingSpeed extends Sprite
    {
        public function CastingSpeed()
        {
            var logger:TextField = new TextField();
            logger.autoSize = TextFieldAutoSize.LEFT;
            addChild(logger);
            function log(msg:*): void { logger.appendText(msg+"\n"); }

            const ITERATIONS:int = 5000000;
            var i:int;
            var beforeTime:int;
            var afterTime:int;

            var bmd:Object = new BitmapData(1, 1);
            var spr:Object = new Sprite();

            beforeTime = getTimer();
            for (i = 0; i < ITERATIONS; ++i)
            {
            }
            afterTime = getTimer();
            log("empty loop: " + (afterTime-beforeTime));

            beforeTime = getTimer();
            for (i = 0; i < ITERATIONS; ++i)
            {
                bmd = bmd;
            }
            afterTime = getTimer();
            log("assignment only: " + (afterTime-beforeTime));

            log("Cast succeeds without assignement:");

            beforeTime = getTimer();
            for (i = 0; i < ITERATIONS; ++i)
            {
                BitmapData(bmd);
            }
            afterTime = getTimer();
            log("\tFunction call style: " + (afterTime-beforeTime));

            beforeTime = getTimer();
            for (i = 0; i < ITERATIONS; ++i)
            {
               	bmd as BitmapData;
            }
            afterTime = getTimer();
            log("\tAs keyword: " + (afterTime-beforeTime));


			log("Cast succeeds:");

			beforeTime = getTimer();
			for (i = 0; i < ITERATIONS; ++i)
			{
				var result : BitmapData = BitmapData(bmd);
			}
			afterTime = getTimer();
			log("\tFunction call style: " + (afterTime-beforeTime));

            beforeTime = getTimer();
            for (i = 0; i < ITERATIONS; ++i)
            {
				if (bmd is BitmapData)
				{
                	var result : BitmapData = bmd as BitmapData;
                }
            }
            afterTime = getTimer();
            log("\tAs keyword with guard: " + (afterTime-beforeTime));

            beforeTime = getTimer();
            for (i = 0; i < ITERATIONS; ++i)
            {
               	var result : BitmapData = bmd as BitmapData;
            }
            afterTime = getTimer();
            log("\tAs keyword without guard: " + (afterTime-beforeTime));

            log("Cast fails:");

            beforeTime = getTimer();
            for (i = 0; i < ITERATIONS; ++i)
            {
                try
                {
                    var result : BitmapData = BitmapData(spr);
                }
                catch (err:TypeError)
                {
                }
            }
            afterTime = getTimer();
            log("\tFunction call style: " + (afterTime-beforeTime));

            beforeTime = getTimer();
            for (i = 0; i < ITERATIONS; ++i)
            {
				if (spr is BitmapData)
				{
                	var result : BitmapData = spr as BitmapData;
                }
            }
            afterTime = getTimer();
            log("\tAs keyword with guard: " + (afterTime-beforeTime));

            beforeTime = getTimer();
            for (i = 0; i < ITERATIONS; ++i)
            {
               	var result : BitmapData = spr as BitmapData;
            }
            afterTime = getTimer();
            log("\tAs keyword without guard: " + (afterTime-beforeTime));
        }
    }
}

results.txt

empty loop: 13
assignment only: 148
Cast succeeds without assignement:
	Function call style: 155
	As keyword: 13
Cast succeeds:
	Function call style: 230
	As keyword with guard: 258
	As keyword without guard: 195
Cast fails:
	Function call style: 12884
	As keyword with guard: 134
	As keyword without guard: 197