When you get an objects morph component with object.GetMorphComponent() Then you start add keys with AddKey all works fine. But when you have added around 50 keys to the timeline with around 18 different morps per frame. The call to AddKey becomes slower and slower. My guess is that AddKey check the keys before somehow and will make: more keys = slower add. Because if you collect the morph keys and then export them as a motion plus clip and remove the morph keys and try add more. It is fast again, until you added around 50 keys again..