With 10 threads at a time - not much, but threads are pretty heavyweight when all you need is waiting on IO. Systems where waiting IO doesn't map 1:1 to threads

With 10 threads at a time - not much, but threads are pretty heavyweight when all you need is waiting on IO. Systems where waiting IO doesn't map 1:1 to threads scale to more concurrent users better (Erlang, Node, Go all do this). With evented IO you can service hundreds of thousands of connections (if you have a good way to round-robin between them or some other way to schedule them well). Having the same number of threads will be difficult.