Performance: spritesheet vs cpu

<font face="Verdana, Arial, Helvetica, sans-serif">Hello! I want the tops of some trees are animated in my game. In each scenario there are approximately 250 trees. Obviously that would encourage all crazy. But I would encourage some. It would be better to encourage are spritesheet or Sine behavior?

Thank you very much!</font> <img src="smileys/smiley1.gif" border="0" align="middle" />

Why not both?..it would probably look better..

A single Animation with as little as 9 frames would do it..for smoothness and then a sine wave angle that is synced to the Animation ...and just use instances

it Shouldnt use too much memory..if you do it right

Ok, I have to prove what you say. :D

Thanks!