I've still run into issues where an external service took approx 1 second per call. We had 20 threads on each docker container running Python. We had a lot of web requests.

It regularly took down the multithreaded python instance.

The solution we went with was to put all the different web requests into 2 flask servers and then take the output of all those different web requests and make one big request tot the django instance that had all the business logic.

If memory serves, we only had 2 flask instances handling all the traffic that the old array of django servers.

Async pays dividends.