[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 root = firstScheduledRoot;
      while (root !== null) {
        const remainingExpirationTime = root.remainingExpirationTime;
        if (remainingExpirationTime === NoWork) {
          
          
          
          
          invariant(
            previousScheduledRoot !== null && lastScheduledRoot !== null,
            'Should have a previous and last root. This error is likely ' +
              'caused by a bug in React. Please file an issue.',
          );
          if (root === root.nextScheduledRoot) {
            
            root.nextScheduledRoot = null;
            firstScheduledRoot = lastScheduledRoot = null;
            break;
          } else if (root === firstScheduledRoot) {
            
            const next = root.nextScheduledRoot;
            firstScheduledRoot = next;
            lastScheduledRoot.nextScheduledRoot = next;
            root.nextScheduledRoot = null;
          } else if (root === lastScheduledRoot) {
            
            lastScheduledRoot = previousScheduledRoot;
            lastScheduledRoot.nextScheduledRoot = firstScheduledRoot;
            root.nextScheduledRoot = null;
            break;