Corporate landings, blogs and service pages are usually read-heavy. An unnecessary SPA can add client JavaScript, hydration and state management, increasing LCP and interaction cost. Astro islands render the page as static HTML and hydrate only genuinely interactive pieces; measure the benefit with bundle analysis and field metrics.
When are islands enough?
- Language toggle, theme, cookie banner, cart badge
- Form wizards and quote calculators
- Lightweight search / filter UIs
- Animated hero (CSS or a small island)
Where you truly need a SPA
A SPA may fit application-heavy flows such as customer panels, real-time dashboards or complex kanban boards. Bundling the marketing site with the panel can complicate deployment and cache management. Where separate lifecycles are needed, consider separating the public site with Astro from an application built with a suitable framework such as Next or React.
Evaluate the technology against content update frequency, visitor tasks, accessibility, measured performance and maintenance capacity. The proposal should explain which interactions are needed and how they will be accepted on the intended devices.
