How do I change the useState without re-rendering it but just its components? Why I need is because I have some logic that changes the useState in Comp1. If I would re-render Comp1 I would have to recalculate its value. But if the change happens I still would like to re-render its components. 

Edit: bigger code snippet. 

```
function Comp1() {
  const [user, setUser] = useState({});

  firebase.auth().onAuthStateChanged(function (_user) {
    if (_user) {
      // User is signed in.
      setUser(_user);
    } else {
      setUser({ exists: false });
    }
  });

  return (
    <div>
      <UserProvider.Provider value={{user, setUser}}>
        <Comp2 />
        <Comp3 />
      </UserProvider.Provider>

    </div>
  );
}

function Comp2(props) {
  const { user, setUser } = useContext(UserProvider);
  return (
    <div>
      {user.exists}
    </div>
  )
}

function Comp3(props) {
  const { user, setUser } = useContext(UserProvider);
  return (
    <div>
      {user.exists}
    </div>
  )
}

//User Provider

import React from 'react';

const UserProvider = React.createContext();
export default UserProvider;

```