Note this thread is very old. Also, we don't have the bandwidth to monitor all the forums for every runtime we support, but if you come on over to the Spine forums, we are happy to help you there!
@evilbert, I'm surprised you are having performance issues, especially without animations playing.
I would first take a look at your skeletons and see if they can be optimized. These pages are relevant:
http://esotericsoftware.com/spine-metrics#Performance
http://esotericsoftware.com/spine-meshes#Vertex-count
Often using Prune weights for all meshes and animation Clean Up for all animations can make a big difference.
Have you profiled where the time is going? You could copy/paste SkeletonAnimation and avoid calling updateWorldTransform if the AnimationState has no animations (or just comment it out to start, to see if it makes a difference).