Svelte Performance Optimization

Svelte 5's fine-grained reactivity provides excellent performance by default, but understanding optimization patterns helps build fast applications at scale.

Reactivity Performance

Fine-Grained Updates

Svelte 5 runes enable granular reactivity—only affected DOM nodes update:

<script>
  let items = $state([
    { id: 1, name: 'Item 1', count: 0 },
    { id: 2, name: 'Item 2', count: 0 }
  ]);