How's Linear so fast? A technical breakdown

5 hours ago

Linear achieves high performance by using a client-side database (IndexedDB) for instant UI updates, with mutations applied locally and synced asynchronously to the server.
Optimistic updates eliminate network waiting times, allowing the UI to respond immediately without spinners or loading states.
Aggressive code splitting, modern bundling (Rolldown/Vite), and preloading techniques reduce initial load times and improve perceived performance.
A service worker caches assets for offline use and faster subsequent loads, while inlined critical CSS and JavaScript in the HTML enable instant rendering of the app shell.
Authentication assumes a happy path, rendering the UI based on local data and handling session validation asynchronously in the background.
The sync engine leverages granular MobX observables for efficient re-renders, ensuring updates affect only changed components rather than entire lists.
Keyboard shortcuts and a command palette enhance user efficiency, making actions fast and accessible without relying on mouse navigation.
Animations are optimized by using only composited properties (e.g., transform, opacity) with short durations to maintain responsiveness.

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