Well, good performance of http request/response cycle is mostly related to async operation, in some form, when long-lived daemon can process big amount of requests without spending time on initialization. Workerman and swoole, powered by async PHP approach, are very fast and suitable for high load. The problem with async PHP, though, is that you need to be careful with libraries (e.g. mysql client) because most of them were designed with short-lived PHP script execution in mind.
