stateless component, purecomponent 리렌더링 이유 비교

번역 및 정리 필요

https://stackoverflow.com/questions/46736983/will-a-stateless-component-re-render-if-its-props-have-not-changed/46737063

https://reactjs.org/docs/optimizing-performance.html

https://reactjs.org/docs/reconciliation.html