In advance, thanks all the guys here to share bunch of valuable information.
As fas as I know, Nodes can't share BoneAnimation if they are in different frame at the same time. (right?)
So I try to use CloneImportExport to clone BoneAnimation.
My model has about 70 BoneAnimations and each BoneAnimation has about 60 frames.
When I share 'boneTransforms' by extending class 'BoneAnimation', it works well.
But If I use CloneImportExport, it consumes too much memory and throws OutOfMemoryError.
I know CloneImportExport maintains references only (by creating CloneCapsule).
But when calling saveClone(), even array members (Vector and Quaternion) in BoneInfluence/BoneTransform created CloneCapsule.
I guess it consumes memory.
I think member variables of ignoreField / shallowCopyField should not be referenced.
Is there any other method to clone data with low memory overhead?