A way to have fast skeleton animations for multiple objects is to use vertex animations baking. See this thread (be sure to read until the end of the thread):
You can try to use refreshBoundingInfo(true, true)
on all your animated meshes to take the bones/morph into account to compute the bounding box. If it’s still not enough, you have the option to set alwaysSelectAsActiveMesh = true
on all the meshes.