When to use this skill

You're building a productivity tool where perceived speed is critical to user experience
Users report the app "feels slow" despite reasonable network latency
You need to eliminate loading spinners and skeleton states from user workflows
You're architecting a local-first application with offline capabilities
You want to implement optimistic updates that feel instant
You're designing a keyboard-first interface for power users

Core principles

The network is the bottleneck—eliminate it wherever possible. Every network request costs hundreds of milliseconds; the best optimization is to avoid the request entirely by reading from local state.
Treat the browser as the database for each user. Store the full workspace in IndexedDB and hydrate into an in-memory observable graph; the UI reads from local state, not the server.
Mutations apply locally first, sync asynchronously. Update the local observable immediately so the UI re-renders synchronously, then queue the transaction for background sync to the server.
Render first, authenticate second. If local data exists, render it immediately and verify the session in the background; only redirect to login if the server rejects.