One of the reasons an asynchronous I/O event loop can be faster than a threaded model is that the CPU spends more of its time in a single userspace thread per c

One of the reasons an asynchronous I/O event loop can be faster than a threaded model is that the CPU spends more of its time in a single userspace thread per core, switching between clients that are ready. A threaded server will incur a kernel-space context switch each time, while an asynchronous loop will keep the processing time in userspace.