How to enhance the tween alpha Performance?(Tween the sprite or the panel?)

[FrankYan]

I wonder what's the differences between tween targets
1.Just Tween alpha of one sprite
2. add a UIWidget as the sprite's parent and tween UIWidget's alpha
3. Tween the Panel's alpha

which one can make best Performance?
Thanks~

[ArenMook]

There shouldn't be any noticeable difference. All methods will require draw call changes.