This article states multiple times that spinning up a process is expensive/very expensive. Is that really true? I ask out of ignorance.

“Compared to other ways of doing parallelism, processes are very expensive, both in terms of taking CPU resources but also the amount of time it takes to spin up a new process.”

“Because it’s expensive to spin up new processes, Postgres will only do this for long-running queries.”

Also:

“There’s been years of people talking about switching Postgres from a process model to a threading model, but nothing concrete has come out of that.”

I’ve read several times that on Linux, the cost between a process and a thread is relatively small.