[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).


if (returnFiber.lastEffect !== null) {
              returnFiber.lastEffect.nextEffect = workInProgress;
            } else {
              returnFiber.firstEffect = workInProgress;
            }
            returnFiber.lastEffect = workInProgress;
          }
        }
        if (__DEV__ && ReactFiberInstrumentation.debugTool) {
          ReactFiberInstrumentation.debugTool.onCompleteWork(workInProgress);
        }
        if (siblingFiber !== null) {
          
          return siblingFiber;
        } else if (returnFiber !== null) {
          
          workInProgress = returnFiber;
          continue;
        } else {
          
          isRootReadyForCommit = true;
          return null;
        }
      } else {
        
        
        
        const next = unwindWork(workInProgress);
        
        if (workInProgress.effectTag & DidCapture) {