[This example](https://codesandbox.io/s/1zn2o513pq) presents a huge performance drop between React 16.2 and React 16.3.

In investigated it and noticed several things:

- Perfomance drop is only visible using development bundle
- This is not related to styled-components (a simple div presents the same problem)
- I tried to investigate in performance tab of Chrome dev tools and I noticed that I get React measures even without "?react_perf"
- React Tree Reconciliation seems very long, do not know why

It is not a big problem for me, but it looks weird, so I decided to [share it on Twitter](https://twitter.com/neoziro/status/979756579296817154),  then @gaearon [invited me to submit an issue about it](https://twitter.com/dan_abramov/status/980036013518139398).


legacyErrorBoundariesThatAlreadyFailed = new Set([instance]);
    } else {
      legacyErrorBoundariesThatAlreadyFailed.add(instance);
    }
  }
  function commitRoot(finishedWork: Fiber): ExpirationTime {
    isWorking = true;
    isCommitting = true;
    startCommitTimer();
    const root: FiberRoot = finishedWork.stateNode;
    invariant(
      root.current !== finishedWork,
      'Cannot commit the same tree as before. This is probably a bug ' +
        'related to the return field. This error is likely caused by a bug ' +
        'in React. Please file an issue.',
    );
    const committedExpirationTime = root.pendingCommitExpirationTime;
    invariant(
      committedExpirationTime !== NoWork,
      'Cannot commit an incomplete root. This error is likely caused by a ' +
        'bug in React. Please file an issue.',
    );
    root.pendingCommitExpirationTime = NoWork;
    const currentTime = recalculateCurrentTime();
    
    ReactCurrentOwner.current = null;
    let firstEffect;
    if (finishedWork.effectTag > PerformedWork) {