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Server Islands: A New Feature for Faster Performance and Personalization in Astro

This is Part 3 of our series on The Future of Astro covering the three major features we have planned for Astro in 2024. This post introduces Server Islands: a new island architecture primitive that lets you deliver static, CDN-cached HTML page shells with injected dynamic content. Frontend performance isn’t the only performance problem you’ll run into on the web. How you deliver a website to the user can be even more impactful than what you deliver, and developers are often forced to make a difficult choice: performance, or personalization? Server Islands are a new primitive that we are exploring for Astro, building on our existing island frontend architecture. You define a server island the same way you would a client island, but instead of using a client:* directive you would use the new server:defer directive instead. Conceptually this is similar to the concept of Suspense in React, Solid, etc. but with the key difference that the deferred island is rendered as a separate HTTP request. Stay tuned for more updates on Server Islands and how it can revolutionize website performance and personalization in 2024 with Astro.