Gatsby is highly regarded for its performance, achieved through several key techniques such as server-side rendering (SSR) at build time, route-based code splitting, and the use of modern APIs. By rendering React components into optimized, pre-rendered HTML during the build process, Gatsby reduces the reliance on JavaScript, leading to faster load times and improved SEO. The platform employs code splitting to ensure that only necessary JavaScript is loaded for each route, enhancing efficiency. Modern browser APIs, like IntersectionObserver and link rel="prefetch", are utilized to prefetch resources, thereby creating a seamless and fast user experience. Gatsby also optimizes images with srcset and responsive design, further contributing to its performance edge. These features, combined with a straightforward deployment process that eliminates the need for server maintenance, make Gatsby a compelling choice for building fast, scalable web applications. Tools like Lighthouse and WebPagetest are recommended for measuring and maintaining performance, reinforcing the importance of continuous validation to ensure consistent speed and reliability.