I assume your application is using a dedicated thread for each request? Even then you would be handling more requests in parallel than the number of cores you

I assume your application is using a dedicated thread for each request? Even then you would be handling more requests in parallel than the number of cores you have, but your concurrency would be limited by the cost of context switching and your memory capacity (having to allocate a sizable stack for each thread in most threading implementations). Queueing is usually required for a stable multi-threaded server, but if you were doing async I/O you wouldn't need it. The extra memory overhead for each extra concurrent request (by means of lightweight coroutine stacks, callbacks or state machines) is not much different from the size it would take on the queue, and there is no preemptive context switching. In most cases, you'll get the same behavior as having a queue here. Cooperative task-switching happens only on async I/O boundaries, so if you're processing a request that requires some CPU-heavy work, your application would just hog a core until it completes the request and then move to the next one.