It also heavily depends on what kind of state you're maintaining, whether any of it needs to be persisted or shared across connections, and how much CPU load th

It also heavily depends on what kind of state you're maintaining, whether any of it needs to be persisted or shared across connections, and how much CPU load the processing outside of pure connection handling will produce. Having a suitable scalability mechanism may be worth more than reduction of per-connection-event CPU cycles. (scaling beyond more than one core, scaling beyond more than one server)