gSkinner came out with this little framework called TweenMax to help ActionScripters with tweening animation.  Let me say, I am a huge fan of it.  I use it on almost all of my projects.  It makes my life very easy and I can write code a lot faster.  Here is the issue, I've been using it so much that if I had to create a tween without it, I wouldn't be able to do it off the top of my head like other code.

Skinner has an AS2 and AS3 version to make programming easier.  TweenMax does it all for you. 

• x/y axis
• alpha
• eases
• onComplete functionality
• onComplete functionality w/ params
• rotation
• tint
• motionBlur
• glow
• blurFilter
• bevelFilter
• Papervision Items
• and many more

What is so special about it, is how easy it is to learn and use.  When you download the TweenMax framework you will receive a swf that you can demo any of the animations and at the bottom of the demo the code will be written for you.  What could be easier than that?  Nothing.  This is why I'm becoming lazy. 

import gs.TweenMax;
TweenMax.to(mc, 1, {x:46, y:43});

If you need to tween multiple items all you have to do is set up a tween for each item, add them to an array and set them to the TweenGroup class.  You can even squence your tweens in any order, add delays between each of them and more.

TweenGroup(tweens:Array, DefaultTweenClass:Class, align:String, stagger:Number)

Or if you want to apply the same tween to the a number of items you can do the following:

TweenGroup.allTo([mc1, mc2, mc3, mc4, mc5], 1, {y:"100", alpha:0, stagger:0.2});

TweenMax is a great framework and worth taking a look at.  It makes coding a lot faster and I haven't had any performance issue I could blame on the framework.  It is worth your time to check it out (http://blog.greensock.com).