This might be a good opportunity to change the server to try out fly.io

Larger pool size only helps if they're freed up quicker than they are used.

I've also observed on other DBs that you can increase the connection pool but it shifts the problem to other resources.

BEAM/Erlang/Elixir's main advantage IMHO is parallelism and "cheap" concurrency that's easy to wrap one's head around. It reuses multiple cores, and processes (lightweight threads) are both cheap (smaller stack size, per-process GC) and easy to get right (due to immutability of data structures and supervision). Also you'll get less spiky latency even under high load.

Node.js main advantages are the breadth of the library ecosystem, industry familiarity and its JIT compiler (if used correctly). At the cost of more setup one can also run an instance per core if they care for parallelism.

So I'd suggest that with BEAM he'd get quite a good performance both in terms of developer time and in serving many (network bound) requests on a multicore machine.

> It is however really really low latency

I've been interested in Erlang for a while, and reading this is intriguing. Taken literally the above makes no sense :) but it also kind of... does, sort of, and I would like to understand how this works.

That honestly makes a lot of sense. Thanks!