Debugging and Performance Optimization

A reducer changed a user's name, the store held the new name, and the screen still showed the old one. This is the reducer:

const profileReducer = (state = { user: { name: 'A' } }, action) => {
  if (action.type === 'rename') {
    state.user.name = action.payload;
    return state;
  }
  return state;
};

Store after dispatch:         B
Renders caused by the action: 0
Text on the screen:           A

That output comes from a store with one development check turned off, using `getDefaultMiddleware({ immutableCheck: false })