Personio, a leading HR solution for small and mid-sized organizations in Europe, successfully transitioned their WordPress monolith to a headless architecture using Vercel + Next.js, resulting in significant improvements to site performance, efficiency, and user experience. The new architecture addressed issues such as cumulative layout shift (CLS) and improved mobile performance, leading to a 29% improvement in Largest Contentful Paint (LCP) score on mobile devices. Additionally, the migration enhanced security by default with features like server-side rendering, static generation, automatic HTTPS, end-to-end encryption, and robust DDoS protection. The transition also upgraded the developer experience within Personio's team, streamlining internal processes and fostering a more collaborative environment, allowing for rapid implementation of new features and updates.