I don't think this is true? At least, I've never seen the issue of OS threads be that context switching is slow. The issue is memory usage, which OS threads ta

I don't think this is true? At least, I've never seen the issue of OS threads be that context switching is slow. The issue is memory usage, which OS threads take a lot of. Would userland scheduling be more CPU efficient? Sure, probably in many cases. But I don't think that's the problem with handling many thousands of concurrent requests today.