Cold starts and lack of mitigation support
7/10 HighServerless cold starts are a major performance pain point on Vercel. Documentation suggests using Edge, but Edge functions don't support Node.js APIs, making them impractical for most use cases, and support for cold start mitigation is severely lacking.
Sources
Collection History
When a compute node scales to zero due to inactivity (typically after 5 minutes), reactivating it can introduce a latency of anywhere from 500ms to a few seconds. I've observed this in testing: a fresh connection to an idle database *will* incur a brief delay.
Edge Functions using Deno experience 200-400 ms cold start times. Latency-sensitive endpoints need warming strategies to stay responsive.
Additionally, serverless cold starts are a huge pain. And support for it is severely lacking. The documentation suggests some basics, and to use edge. But edge is hardly useful and highly situational as it does not support node apis.