[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).


) {
      info +=
        ' You likely forgot to export your component from the file ' +
        "it's defined in, or you might have mixed up default and " +
        'named imports.';
    }
    const ownerName = owner ? getComponentName(owner) : null;
    if (ownerName) {
      info += '\n\nCheck the render method of `' + ownerName + '`.';
    }
  }
  invariant(
    false,
    'Element type is invalid: expected a string (for built-in ' +
      'components) or a class/function (for composite components) ' +
      'but got: %s.%s',
    type == null ? type : typeof type,
    info,
  );
}
export function createFiberFromFragment(
  elements: ReactFragment,
  mode: TypeOfMode,
  expirationTime: ExpirationTime,
  key: null | string,
): Fiber {
  const fiber = createFiber(Fragment, elements, key, mode);
  fiber.expirationTime = expirationTime;
  return fiber;
}