I thought you said "spine with no animation". Which is it?
Just play the animation, subscribe to the track's Complete event, and disable it with that.
It looks like this:
void PlayTheAnimationThenStopUpdating () {
mySkeletonAnimation.enabled = true;
mySkeletonAnimation.state.SetAnimation(0, myAnimation, false).Complete += delegate {
mySkeletonAnimation.enabled = false;
};
}
You could also permanently subscribe to Spine.AnimationState's Start and End or Complete events to enable and disable the component in a similar way as above.
but it would be mySkeletonAnimation.state.Start
or .Complete
or .End
depending on your use.
Find more about those events here: Complete vs End (Runtime Events)
If you need more optimization than that, you're always free to modify the runtime in your project, but don't assume that it applies to everyone unless it actually does, so there shouldn't be an expectation that your changes should be in the official runtime.