[tom_]

You're doing nothing wrong other than using async. You'll only become an async fan once you write a program that does no interesting CPU work, just a lot of I/O - because async is great for the case where the computer spends most of its time waiting around for multiple (or possibly even quite a lot more than that) I/O requests to complete, then does a bit of CPU work on completion of each in order to decide what I/O to do next. Then repeat forever.

This stuff is always a pain to do in languages that don't have this sort of facility, because you need to manually structure your code as some kind of state machine. But that's exactly the sort of tedious nonsense the computer can do for you, if only there's the language mechanism to let you explain to it what you want - which is exactly what async is for.

But it is fundamentally a cooperative multitasking mechanism, as code written in this manner expects to run atomically between awaits. So it's impossible for it to take advantage of multiple threads as-is, which is why languages supporting this mechanism don't bother.

If you are doing a lot of CPU work, that's a problem that async was never designed to solve. You need threads.