Next.js App Router: what it actually means for your website

If you have had a conversation with a web developer recently, you have probably heard the term App Router. It is the new way Next.js handles pages, and it became the default with Next.js 13. But what does it actually mean for a business owner or marketing lead who just wants a fast website?

The short version: App Router enables React Server Components, which means large parts of your website can be rendered on the server and sent to the browser as plain HTML — with no JavaScript required on the client side to display them. This is a meaningful performance change. Less JavaScript means faster parse times, faster interaction readiness, and better scores on Core Web Vitals like LCP (the metric Google uses most heavily in ranking signals).

The practical impact is a site that loads fast for everyone, not just people with fast connections and modern phones. A marketing page built with App Router and server components can score a Lighthouse performance of 97 or higher without any manual optimisation work. The same page built with client-side rendering typically scores 50–70 out of the box and requires a performance sprint to get close to passing.

For non-technical stakeholders, the question to ask your developer is simple: are you using the App Router with React Server Components by default, or are you using client components for pages that do not need interactivity? If it is the latter, you are leaving performance on the table — and potentially leaving ranking signals on the table too. It is worth asking before the project starts rather than after the first Lighthouse audit.