Development runserver has been multithreaded by default for over a decade. I think you need to go back to major version 1 to see it single-threaded by default. Maybe affected by the GIL though.
True, but in this case with SQLite, there's unlikely to be much of a difference because there isn't the spare time available when waiting for a separate database server. I don't know what providers are good for a $10/month instance these days.
How are you spending any non-negligible time reading from SQLite at 12 requests per second though? That would mean you’re spending something like 50 ms per request on reading from SQLite.