Rendering Strategies: SSG, ISR & Islands Architecture

For editorial websites, blogs and landing pages without frequently changing or personalised content, SSG is usually the fastest and cheapest choice, because there are no server costs for rendering at runtime. ISR suits content that changes regularly, product prices or news for example, but does not need to be accurate to the second: once the revalidation window has passed, the next visitor still receives the cached version immediately while a new one is generated in the background, so time to first byte does not suffer. Only a genuine cache miss – a page that has never been pre-generated and is created on request – is noticeably slower. The islands architecture is particularly interesting for content-heavy pages with few interactive elements, such as an ordering widget or a slider, because Astro pages are often delivered entirely without JavaScript and only the islands themselves load script code. When rebuilding a website technically, choose the rendering strategy on the basis of the actual content type, since pure SSR solutions are often oversized when content rarely changes. For a relaunch it is worth checking whether a hybrid approach, with SSG for content pages and ISR or SSR only for dynamic areas such as the basket or login, reduces load times and hosting costs at the same time.