Ship apps faster with GitHub, Vercel, and Firestore

The cold start reality
While the industry has made massive strides in minimizing initialization times—particularly with lightweight edge networks—traditional Node.js-based serverless functions still experience cold starts. If a function has not been invoked recently, or if traffic spikes require a new instance to spin up concurrently, the first request will take a noticeable latency hit as the container provisions and the code loads.
API instead of RAM
In a traditional server environment, you can store transient data in global RAM, allowing subsequent requests to access shared context instantly. In the serverless model, every request might hit a fresh container. Therefore, all shared context must be externalized. Although Firestore serves brilliantly as the state manager, relying on a database for high-frequency, sub-millisecond, ephemeral caching introduces network latency and per-operation costs. That said, using a shared RAM state on a server is non-trivial also, unless you are using a single app server and VM (because high-availability or fail-over requirements will lessen the RAM win on a traditional server).
Tuning for velocity and control
Every architectural decision is a trade-off. There are no cost-free choices. By adopting the GitHub, Vercel, and Firestore stack, you are explicitly maximizing feature velocity over fine-grained control.