[imtringued]

>You've just deoptimized your app, and your whole component will re-render on every change.

If you have 3 useState each of those will use 3 useReducer internally (every hook is implemented on top of useReducer), If you consolidate them into one useReducer then you will end up with the same thing performance wise. Maybe even better. Whenever an event is pushed into the hook's queue it marks the component as dirty. The next call to useReducer will then reduce all unprocessed events into the current state. It's entirely possible that having less hooks and therefore less metadata in the background can improve performance more than avoiding the theoretical cost of rerendering a component that most likely would have to be rerendered anyway.

[jsmith45]

Not all hooks are implemented in terms of reducers. `useMemo`, `useCallback`, `useRef` for example are not based on reducers, (or effects). Obviously the effect hooks are based on effects not reducers, and some like ` useDeferredValue` are based on both.

But you certainly are correct that useState is reducer based. I'm pretty sure one is only avoiding rerender via using multiple `useState` if they don't implement the reducer in a way where it returns the original object when there was no net change. If you are able to implement the such that it only returns a new object when there really is a change, then a single useReducer call is strictly more efficient than multiple useStates. (This might require more complicated code, as returning a new object every time is often the easy way to implement reducers.)