I had the same experience. I have a Next.js app and Postgres DB I host on a server-ful PaaS. I hosted the same app on Vercel with Neon DB and the app was significantly slower. The first time Neon is connected, it will be slow so I was prepared for that. Consequent reloads and using the app normally was slow too. Maybe integrating Neon directly with Vercel will fix these issues.

I just don’t see the value prop to use Vercel for SaaS apps. Using a running server for those works better, cheaper, and faster. For consumer-facing storefronts, Vercel is a no-brainer though.