title: React: Is manual memoization necessary?
body: <p>Reading through <a href="https://github.com/reactjs/react-basic#memoization" rel="noreferrer">React - Basic Theoretical Concepts</a> and the upcoming <a href="https://github.com/acdlite/react-fiber-architecture/blob/master/README.md" rel="noreferrer">React Fiber Architecture</a>, it seems memoization plays an important central part in the React data handling logic along with immutable data stores.<br>
  However, what is not immediately obvious is whether and to what extent is memoization handled internally by React and if and when should a developer memoize manually?</p>
  
  <p>Shortly put, when does React internally memoize function calls and when should a developer do so themselves? Does React memoize any non-internal function calls automatically at all?</p>