[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).


ClassComponent,
  HostRoot,
  HostComponent,
  HostText,
  HostPortal,
  CallComponent,
  ReturnComponent,
  ForwardRef,
  Fragment,
  Mode,
  ContextProvider,
  ContextConsumer,
} from 'shared/ReactTypeOfWork';
import getComponentName from 'shared/getComponentName';
import {NoWork} from './ReactFiberExpirationTime';
import {NoContext, AsyncMode, StrictMode} from './ReactTypeOfMode';
import {
  REACT_FORWARD_REF_TYPE,
  REACT_FRAGMENT_TYPE,
  REACT_RETURN_TYPE,
  REACT_CALL_TYPE,
  REACT_STRICT_MODE_TYPE,
  REACT_PROVIDER_TYPE,
  REACT_CONTEXT_TYPE,
  REACT_ASYNC_MODE_TYPE,
} from 'shared/ReactSymbols';
let hasBadMapPolyfill;
if (__DEV__) {
  hasBadMapPolyfill = false;
  try {