React Context vs Zustand: When to use which one
Developers often make one mistake with React state. They use Context incorrectly and then blame Context for performance issues.
The problem is usually one large context object. When a value in that object changes, every component using that context re-renders. Even if a component only needs one small piece of data, it still reacts to every change in the object.
If your notifications update every 30 seconds, your Navbar re-renders even if the Navbar only cares about the user name. This kills performance.
You can fix this without a library. Split your contexts by how often they change.
Instead of one big context, use several: • UserContext for user data • UIContext for sidebar state • NotificationContext for alerts
Now, your Navbar only re-renders when the user data changes. This simple split solves most performance complaints.
Use React Context for stable values: • Themes • Auth status • Language settings
Context also works well with Server Components. Zustand works only on the client side.
Use Zustand when you need selective subscriptions. Zustand allows components to subscribe to specific slices of state. If one part of your store changes, only the components watching that specific part re-render.
Follow this logic for new state:
Use React Context if: • The data is stable (theme, auth, locale). • You need it to work with SSR or Server Components. • You want to stop prop drilling by splitting contexts.
Use Zustand if: • The data changes frequently. • Components need to watch specific slices of state. • Your logic is complex.
Wait. Do not use either for API data. If you are fetching data from a server, use TanStack Query. Context and Zustand do not handle caching or background refetching.
Summary: • One big context object causes re-renders. Split it. • Using Zustand for stable values is overkill. • Using Context for frequent changes causes lag. • Using Zustand for server state is the wrong tool.