Partial Hydration is a new beta feature in Gatsby 5 that aims to improve site performance by selectively hydrating only necessary components on the client-side, rather than hydrating the entire page. This feature, built on React Server Components, allows developers to specify which components require full interactivity and which can remain static, reducing JavaScript bundle sizes and subsequently enhancing the time to first interaction. While Partial Hydration offers significant performance benefits, it is still in beta due to its reliance on experimental features of React Server Components, and certain limitations, such as incompatibility with Slices, remain. Developers interested in leveraging Partial Hydration are encouraged to explore the Gatsby documentation and starter projects to better understand its implementation, while keeping in mind that the technology is subject to change before its full release.