title: Bad performance with core animation and view rotations: How to improve?
body: <p>I have 12 views which I rotate almost similar to the icons in the home screen when going into homescreen-customization-mode by touching an icon for a few seconds.</p>
  
  <p>I use a 3D transformation code to do the rotations. They have each a duration of just 0.02 seconds, and the angle and direction of rotation changes permanently upon acceleration measurements.</p>
  
  <p>5 of those views are fine, but 12 have a very bad performance. Here's the rotation code:</p>
  
  <pre><code>CATransform3D rotatedTransform = CATransform3DRotate(CATransform3DIdentity, degrees * M_PI / 180.0, 0.0f, 0.0f, 1.0f);
  self.layer.transform = rotatedTransform;
  </code></pre>
  
  <p>there's some core animation wrapped around it. But I see a waste of CPU here, since I don't do any 3D stuff. I really only rotate 2D and nothing else. They're simple UIImageViews, but a custom class that does this rotation animations on her own.</p>
  
  <p>I've heared that there are "affine" transforms which are supposed to work for the 2D space. Would you advise to change that to 2D in this case?</p>
  
  <p>Must I prefer to change the transform of the layer, or of the view? which is faster? </p>