The Hidden Cost of Global Stores in Vue (and When They’re Still Worth It)
Source: Dev.to
Why Global Stores Feel Attractive
- Centralized place for state – a single source of truth.
- Excellent DevTools integration – easy inspection and time‑travel debugging.
- Type safety – especially when using TypeScript.
- Simple APIs – actions and getters are straightforward to use.
Common Misuses of Pinia
Anti‑pattern: Storing Local or Temporary State
A very common mistake is placing state that belongs to a single component or view into a Pinia store simply because the store is available.
Typical examples
- Modal open/close state
- Form input values
- Page‑specific filters
- Temporary loading flags
Consequences
- Bloated stores – they accumulate unrelated pieces of state.
- Unclear ownership – it becomes hard to tell which component “owns” a piece of data.
- More indirection – components must go through the store for simple local concerns.
- Harder refactoring – changes ripple through the store and affect unrelated parts of the app.
If a piece of state only belongs to a single component tree or route, keeping it local is often simpler and healthier.
Dependency Creep
Implicit Dependencies
Every time a component imports a store, it creates an implicit dependency on:
- The store’s structure
- Its internal logic
- Side effects (e.g., API calls)
- Its lifecycle
Long‑term Effects
- Components become harder to reuse.
- Tests require more mocking.
- Changes in one store can unintentionally affect many unrelated components.
What starts as convenience slowly turns into architectural gravity, pulling unrelated concerns into the same global layer.
Performance Implications of Global Reactivity
Reactive Overhead
Global stores are reactive by default, meaning:
- Any reactive property can trigger updates.
- Any component using the store participates in its dependency graph.
When It Hurts
Issues arise when:
- Large objects are stored globally.
- Stores are deeply reactive without need.
- Components subscribe to more state than they actually use.
These situations can cause:
- Unnecessary re‑renders.
- Expensive computed recalculations.
- Subtle performance regressions.
While utilities like shallowRef or splitting stores can mitigate the problem, the best optimization is often not to globalize the state in the first place.
When Global Stores Are Still Worth It
Ideal Use Cases
- State must persist across routes.
- Multiple distant components depend on the same data.
- Centralized caching or synchronization is required.
- Debugging via DevTools matters.
- The state truly represents an application‑wide concern (e.g., authentication, feature flags, global UI preferences, shared cached API data, notifications).
Scope Discipline
- Keep stores small and focused.
- Avoid dumping UI‑only state into them.
- Expose a minimal reactive surface as the store’s public API.
- Treat stores as part of your library’s contract, not as a generic data bucket.
Conclusion
Global stores are powerful — but power requires restraint. Used intentionally, they simplify your architecture. Used carelessly, they quietly erode it. Keep the intent clear, limit the scope, and let local state remain local when appropriate.
Happy coding! 🖥️