Why We Build Every Website with Astro (And Why the Numbers Back It Up)

If you’ve been wondering why a web agency would commit fully to a single framework, here’s the short answer: Astro is the only framework where performance is the default — not an achievement.

Every other popular framework ships JavaScript to the browser whether you need it or not. WordPress loads plugins and themes that run on every page. Next.js and Nuxt hydrate the entire page client-side. The result is heavy, slow sites that frustrate users and confuse search engines.

Astro takes the opposite approach.

The numbers first

Before we get technical, here are the numbers that matter:

63% of Astro websites pass Core Web Vitals — the benchmark Google uses to assess page experience
Compare: WordPress 44%, Gatsby 42%, Next.js 27%, Nuxt 24%
Every 100ms faster your site loads, you gain 1% more conversions — a well-documented industry finding
53% of mobile users abandon a page if it takes more than 3 seconds to load
Up to 60% smaller image files with Astro’s automatic WebP/AVIF optimisation

Source: HTTP Archive and Chrome UX Report, cross-referenced with Google’s Core Web Vitals research.

These aren’t cherry-picked benchmarks. They reflect the real-world experience of websites built with each framework, measured across millions of pages.

Zero JavaScript by default

The core philosophy behind Astro is radical: ship no JavaScript unless you explicitly need it.

Traditional web frameworks work like this: the server sends JavaScript to the browser, the browser downloads it, parses it, executes it, and then you see your page. This process — called hydration — adds hundreds of milliseconds to every page load, even if the page itself has no interactive features at all.

Astro skips that entirely. Pages are rendered to pure HTML and CSS at build time. The browser receives a complete, fully-rendered document. Nothing to parse. Nothing to execute. The page appears immediately.

If you do need interactivity — a mobile menu, a contact form, a slider — Astro handles that through Islands.

Astro Islands: maximum performance through intelligent decoupling

The Islands Architecture is the technical idea that makes Astro genuinely different.

Instead of treating your whole page as a JavaScript application, Astro identifies interactive elements as isolated “islands” embedded in a sea of static HTML. These islands load selectively:

Only when the user can see them (client:visible)
Only when the browser is idle (client:idle)
Only immediately if absolutely required (client:load)

Here’s what a typical Astro page looks like structurally:

Section	Type	JavaScript?
Header with mobile menu	Island	Yes — loaded on demand
Hero	Static HTML	None
About section	Static HTML	None
Services grid	Static HTML	None
Contact form	Island	Yes — loaded when visible
Footer	Static HTML	None

Most of the page is pure HTML. Search engines read it instantly. The browser renders it instantly. Only the parts that actually need JavaScript get it — and only when needed.

Why this matters for SEO

Google’s Core Web Vitals algorithm directly affects your search rankings. The three main signals are:

Largest Contentful Paint (LCP) — how quickly the main content appears. Astro’s static HTML means LCP is almost always under 1 second. WordPress pages with heavy plugin stacks regularly exceed 4 seconds.

Cumulative Layout Shift (CLS) — whether elements jump around as the page loads. Astro’s predictable static output eliminates the layout shifts caused by deferred JavaScript execution.

Interaction to Next Paint (INP) — how responsive the page feels. Islands architecture means only the minimum JavaScript is loaded, so the browser has more resources to respond to user input.

The result: 63% of Astro sites pass all three Core Web Vitals. That’s the highest pass rate of any major web framework.

Image optimisation built in

One of the most overlooked performance issues on modern websites is image weight. A WordPress site with a theme that hasn’t been carefully configured can easily ship JPEG images at 2–4× the file size needed.

Astro’s built-in <Image /> component handles this automatically:

Converts images to WebP or AVIF format — up to 60% smaller than JPEG at the same visual quality
Adds responsive srcset attributes so mobile devices download appropriately sized images
Applies lazy loading to images below the fold
Prevents layout shift with automatic width and height attributes

No plugins to configure. No third-party services to pay for. It’s part of the framework.

Framework agnostic — bring what you know

One concern agencies hear about Astro: “But our team knows React.”

Astro is framework agnostic. You can use React, Vue, Svelte, Solid, or Preact components inside Astro — even mixed within the same page. Each component becomes an Island when it needs interactivity.

This means:

Existing component libraries work out of the box
Teams can gradually migrate existing React/Vue codebases to Astro without rewriting everything
You can bring specialised UI components from any ecosystem

The framework doesn’t force you to abandon your tools. It gives your existing tools a better performance foundation.

Deploy anywhere — for free

Astro generates pure static files: HTML, CSS, and minimal JavaScript. These can be deployed to any static hosting platform:

Vercel — zero monthly cost for most small business sites
Netlify — similarly free for most use cases
Cloudflare Pages — globally distributed edge hosting, free tier
AWS S3 + CloudFront — enterprise-grade for high-traffic sites

Most of our clients pay £0/month in hosting costs. Compare that to WordPress (which needs a PHP server, database, and typically costs £20–80/month) or Webflow (which charges £25–40/month in platform fees, in addition to any custom domain costs).

Over three years, a Webflow site costs £900–1,440 in platform fees alone — before any development work.

Content management without a CMS tax

WordPress sites often become slow because content editors need plugins to do basic things — page builders, form plugins, SEO plugins, caching plugins. Each plugin adds more JavaScript, more database queries, more attack surface.

Astro uses Content Collections — a typed, structured way to manage content in Markdown files, validated at build time. For teams that want a CMS interface, lightweight headless options like Tina CMS or Decap CMS sit on top of Astro without adding platform lock-in or monthly fees.

Your content lives in your Git repository. You own it completely.

Should your site be built with Astro?

Astro is the right choice if:

Your site is content-focused (business site, portfolio, blog, landing pages)
Page speed and SEO are priorities for your business
You want to stop paying monthly platform fees
You want to own your code and your content outright
You’re migrating from a slow WordPress or expensive Webflow site

It’s worth considering alternatives if:

You’re building a complex SPA with heavy client-side state (a dashboard, a web app)
Your team is deeply committed to a Next.js or Nuxt architecture and the migration cost outweighs the gain

For the vast majority of business websites — the kind that need to look professional, load fast, rank on Google, and convert visitors into enquiries — Astro is the right framework. The data agrees.

Want to know whether Astro is the right fit for your project? Get in touch — we’ll give you an honest assessment, no sales pitch.