[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).


stopWorkLoopTimer(interruptedBy);
    interruptedBy = null;
    isWorking = false;
    
    if (didFatal) {
      
      if (__DEV__) {
        stack.resetStackAfterFatalErrorInDev();
      }
      return null;
    } else if (nextUnitOfWork === null) {
      
      if (isRootReadyForCommit) {
        
        root.pendingCommitExpirationTime = expirationTime;
        const finishedWork = root.current.alternate;
        return finishedWork;
      } else {
        
        invariant(
          false,
          'Expired work should have completed. This error is likely caused ' +
            'by a bug in React. Please file an issue.',
        );
      }
    } else {
      
      
      return null;