&gt; 40k&#x2F;sec http requests (no pipelining) per core is about as fast as it gets unless you move TCP into user space.<p>I think it can be micro-optimized beyond that. With predictions to avoid unnecessary syscalls, with syscalls grouped together to make cpu more efficient for the rest of the time it spends in event loop, and if it&#x27;s possible to modify kernel a bit - with batching syscalls together to make them very cheap.