[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).


let isCommitting: boolean = false;
  let isRootReadyForCommit: boolean = false;
  let legacyErrorBoundariesThatAlreadyFailed: Set<mixed> | null = null;
  // Used for performance tracking.
  let interruptedBy: Fiber | null = null;
  let stashedWorkInProgressProperties;
  let replayUnitOfWork;
  if (__DEV__ && replayFailedUnitOfWorkWithInvokeGuardedCallback) {
    stashedWorkInProgressProperties = null;
    replayUnitOfWork = (failedUnitOfWork: Fiber, isAsync: boolean) => {
      
      Object.assign(failedUnitOfWork, stashedWorkInProgressProperties);
      switch (failedUnitOfWork.tag) {
        case HostRoot:
          popHostContainer(failedUnitOfWork);
          popTopLevelLegacyContextObject(failedUnitOfWork);
          break;
        case HostComponent:
          popHostContext(failedUnitOfWork);
          break;
        case ClassComponent:
          popLegacyContextProvider(failedUnitOfWork);
          break;
        case HostPortal:
          popHostContainer(failedUnitOfWork);
          break;
        case ContextProvider:
          popProvider(failedUnitOfWork);
          break;
      }