It will diff the virtual dom, but you'll still be running the `render()` method again for every component. That is, unless you replace it with a PureComponent t

It will diff the virtual dom, but you'll still be running the `render()` method again for every component. That is, unless you replace it with a PureComponent that does shallow diffing, write your own `shouldComponentUpdate` (if still using classes), or use something like Redux that will actually manage updates outside of React's component lifecycle and take advantage of immutable data structures.