The BFCM (Black Friday-Cyber Monday) dashboard is a data-heavy, real-time application built using Next.js and a modified polling architecture. The core of the site works by having the client poll the server for data every 10 seconds. To overcome challenges in building this dashboard, the team used various optimizations such as cost-efficiency measures like using a rolling window to minimize expensive queries, incremental static regeneration (ISR) to reduce database calls, dynamic visuals with rate-of-change tactics to provide a smooth user experience, and ensuring accuracy by adjusting the rate of change dynamically. Additionally, they moved data fetching to the server for better performance using React Server Components (RSCs). By addressing these performance bottlenecks one step at a time, the team was able to create a cost-efficient, performant, accurate, and user-friendly dashboard that showcases Vercel's infrastructure and capabilities.