The $5/month VM I rent has 2 CPUs. And you want to overcommit because of IO blocking.

Anyway, more than a decade ago my django servers could handle close to 10 requests per second on each thread.

You can run multiple OS threads (gunicorn workers) on one VM thread so the workers don’t have to wait for each others request to finish though, right?

And if you pay $10/month for a single threaded machine, you’re overpaying by a lot.

For a cheap VM, I'd still be expecting in the range of 500-1000 connections a second. Green threads are cheap, even with a single processor.

For a half-decent VM, I'd be expecting multi-thousand.

Single figures a second, is choked to a single connection at a time.