Deferred Static Generation (DSG), introduced in Gatsby 4, impacts SEO by balancing developer and user experiences, particularly in relation to Google's Core Web Vitals. Google evaluates these vitals—Loading (Largest Contentful Paint), Interactivity (First Input Delay), and Visual Stability (Cumulative Layout Shift)—through data collected from Chrome and Android users, affecting how website performance is ranked. DSG allows specific pages to be built at runtime upon the first request, mimicking Server-Side Rendering (SSR) for that initial load, but then serving subsequent requests with statically generated pages, akin to Static Site Generation (SSG). This results in most users experiencing the speed and performance benefits of a static site, which aligns with Google's performance criteria. Consequently, while the first visit to a deferred page may load slower, the overall impact on Core Web Vitals is minimal, offering marketers and developers an optimized balance without compromising SEO performance.