I was just tinkering and wondered what would be quicker, using clone() on a Rectangle or just copying each property by hand.

Totally blown away by the difference,

import flash.utils.getTimer;
import flash.geom.Rectangle;

var time:Number = getTimer();

function runClone():void{    
    var rect:Rectangle=new Rectangle(0,0,100,100);
    var destRect:Rectangle=rect.clone();
    time = getTimer();
    for (var i:int = 0; i < 10000000; i++) {
        destRect=rect.clone();
    }
    trace("runClone: ", (getTimer()-time));
}

function runCopy():void{    
    var rect:Rectangle=new Rectangle(0,0,100,100);
    var destRect:Rectangle=rect.clone();
    time = getTimer();
    for (var i:int = 0; i < 10000000; i++) {
        destRect.x=rect.x;
        destRect.y=rect.y;
        destRect.width=rect.width;
        destRect.height=rect.height;
    }
    trace("runCopy: ", (getTimer()-time));
}

runClone();
runCopy();

And here's my results ( Please feel free to post your own, or to point out anything dumb I may have done to affect the outcome )

runClone:  11567
runCopy:  65

Squize.