That's a problem - but its one that is common to all kinds of framework which make use of cooperative multitasking - whether they are in Python, Java (Netty, NI

That's a problem - but its one that is common to all kinds of framework which make use of cooperative multitasking - whether they are in Python, Java (Netty, NIO, etc), C (Nginx, libevent, ...), C# or Rust. All those frameworks trade off high performance if everything is well behaved against easy of use and potential of very bad performance if some regression is introduced. Whether that tradeoff ia a good one to take will depend on the application.