useState vs useReducer vs Zustand: I Built the Same Feature Three Ways (With Live Render Counts)

"Should I use useState, useReducer, or a store like Zustand?" usually gets answered with vibes. So I built all three running the same feature, side by side, with live render counts — because the thing that actually drives the decision is invisible until you watch it.

▶ Live demo: https://state-mgmt-compare.vercel.app/
Source (React 19 + real Zustand): https://github.com/dev48v/state-mgmt-compare

Two views read two slices — count and name. Click "bump count" in each column and watch the per-view render counters.

The part everyone gets backwards

useState vs useReducer is not a performance decision. They re-render identically. It's an organisation decision — a pile of setX calls vs one reducer that handles related transitions in one place. Use a reducer when several values change together or the transitions get gnarly; use useState otherwise. That's it.

The decision that actually affects re-renders is Context vs an external store:

// Context: ANY change to the value re-renders EVERY consumer
const { count } = useContext(AppCtx);   // re-renders when name changes too
// Zustand: subscribe to a SLICE — re-render only when THAT slice changes
const count = useStore((s) => s.count); // ignores name changes

In the demo, bumping count:

• useState + Context → count view ×3, name view ×3 (both re-render)
• useReducer + Context → ×3 / ×3 (identical — told you)
• Zustand → count view ×3, name view ×1 (never re-rendered)

That ×1 is the whole point. Zustand's selector subscribes the component to one slice of the store, so unrelated updates skip it — with no provider and no prop-drilling. To get the same result with Context you'd reach for React.memo, useMemo on the value, or splitting into multiple contexts.

So which one?

Use the simplest thing that fits. Reach for Zustand when state is shared widely and Context re-renders start to hurt — not before.

Real React, real Zustand, live counters. If it settled the question for you, a star helps others find it: https://github.com/dev48v/state-mgmt-compare