[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).


workInProgress: Fiber,
    renderTime: ExpirationTime,
  ) {
    if (renderTime !== Never && workInProgress.expirationTime === Never) {
      
      
      return;
    }
    
    let newExpirationTime = getUpdateExpirationTime(workInProgress);
    
    
    let child = workInProgress.child;
    while (child !== null) {
      if (
        child.expirationTime !== NoWork &&
        (newExpirationTime === NoWork ||
          newExpirationTime > child.expirationTime)
      ) {
        newExpirationTime = child.expirationTime;
      }
      child = child.sibling;
    }
    workInProgress.expirationTime = newExpirationTime;
  }
  function completeUnitOfWork(workInProgress: Fiber): Fiber | null {
    
    
    
    while (true) {