We're dealing with fundamental limitations of I/O though, which is causing the delays.

I want to write stuff to disk (SSD these days). I can issue a request, then have to wait tens to hundreds of milliseconds (in the average case, the worst case can be far longer) for that request to finish and let me know that my I/O request succeeded or failed. There's no getting around that with present-day technology.

The situation is worse and even less reliable with network I/O. If you are talking to a server in another continent, the speed of light determines the minimum of time I hear back from it, even if it (and all the intermediary network links) are lightly loaded and functioning perfectly.