SvelteKit vs Astro
Side-by-side comparison of 2 ecommerce template stacks. Every dimension reflects real production measurements and real trade-offs — no marketing fluff.
SvelteKit
SvelteKit compiles components to vanilla JS at build time — there's no framework runtime shipped to the browser. The result is the smallest bundle and best Core Web Vitals of any stack in the catalog. If performance is non-negotiable, this is the stack.
What you gain
- Smallest first-party JS bundle of any web framework — ~40 KB gzipped for a product page
- Form actions give you progressive enhancement automatically — stores work without JavaScript
- Svelte 5 runes make reactivity explicit and TypeScript-friendly
- Vite gives the fastest dev server in the ecosystem
Trade-offs
- Smaller component library ecosystem — you'll write more UI code yourself
- Fewer third-party integrations for auth, payments, and analytics compared to React/Vue stacks
- Smaller hiring pool — harder to find experienced Svelte engineers
Performance
Mobile LCP around 1.7s — the fastest web framework in the catalog. The compile-away-the-runtime approach pays off on every page load.
SEO positioning
Excellent. SSR-first with the lowest JavaScript overhead. Google indexes pages as fast as any other framework and Core Web Vitals are consistently the best of any stack.
Astro
Astro's islands architecture ships zero JavaScript by default and only hydrates the components that need interactivity. For content-heavy stores — catalog browsing, editorial product pages, long-form marketing — this produces the best Core Web Vitals of any framework, beating even SvelteKit on content pages.
What you gain
- Zero-JS default — pages ship as pure HTML + CSS unless a component explicitly needs hydration
- Best mobile Core Web Vitals in the catalog for content-heavy pages
- Hybrid rendering (SSG / SSR per route) — use SSG for content, SSR for product pages
- Framework-agnostic — you can use React, Vue, Svelte, or Solid components in the same project
Trade-offs
- Islands architecture requires more thought about hydration boundaries
- Not ideal for highly interactive stores where every page needs heavy client-side state
- Cart state typically lives in an interactive island — more setup than in Next.js
Performance
Mobile LCP ~1.6s and Lighthouse score ~98. The best content-page performance of any stack. Interactive pages (cart, checkout) match SvelteKit; content pages beat it.
SEO positioning
Excellent. The zero-JS-default approach means Google renders pages without executing any JavaScript, which is the fastest indexing path. If organic search is your primary revenue channel AND your store is catalog-heavy, Astro is the strictly best choice.
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