getBoundingClientRect is called during react reconciliation on an unmount

[MarcPorciuncula]

componentWillUnmount() {
  controller.unmount(this.props.id, this.ref.getBoundingClientRect());
}

According to (the React docs)[https://facebook.github.io/react/docs/react-component.html#componentwillunmount], componentWillMount, is called immediately before the root dom node associated with the component is removed from the dom, meaning during reconciliation. If it is called during reconciliation, it's entirely possible that layout changes have already been applied to the dom when the bounding rectangle is measured, resulting in animations based on incorrect positions. Additionally, getBoundingClientRect forces a paint during reconciliation, which could cause major performance issues.