[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).


isRendering = false;
  }
  function completeRoot(
    root: FiberRoot,
    finishedWork: Fiber,
    expirationTime: ExpirationTime,
  ): void {
    
    const firstBatch = root.firstBatch;
    if (firstBatch !== null && firstBatch._expirationTime <= expirationTime) {
      if (completedBatches === null) {
        completedBatches = [firstBatch];
      } else {
        completedBatches.push(firstBatch);
      }
      if (firstBatch._defer) {
        
        
        root.finishedWork = finishedWork;
        root.remainingExpirationTime = NoWork;
        return;
      }
    }
    
    root.finishedWork = null;
    root.remainingExpirationTime = commitRoot(finishedWork);
  }
  
  
  function shouldYield() {