That's a very good question — I feel like the article is set up in a way that you could easily take the TCP-based, hand-written server and try to match Axum/hyp

That's a very good question — I feel like the article is set up in a way that you could easily take the TCP-based, hand-written server and try to match Axum/hyper's performance — implement keep-alive, be smarter about buffering, etc, and see what makes an actual difference. Of course if you reach a point where the only thing left to do is implement http/2, that... is no longer an evening project