Animancer.AnimancerLayer.GetOrCreateWeightlessState(Animancer.AnimancerState) is cloning a complex state such as a Animancer.ManualMixerState or Animancer.ControllerState. This has a larger performance cost than cloning a Animancer.ClipState and these states generally have parameters that need to be controlled which may result in undesired behaviour if your scripts are only expecting to have one state to control.

CloneComplexState