It is ultimately a failure of language and runtime that programmer has to manually specify where he wants to make asynchronous vs. synchronous functions to get the optimal performance.

This blog posts elaborates on that better then I could do here, so I'm just going to link to it: http://journal.stuffwithstuff.com/2015/02/01/what-color-is-y...

> that programmer has to manually specify where he wants to make asynchronous vs. synchronous functions to get the optimal performance.

programs aren't just pure computations. There are plenty of times when you want a specific event to happen at a specific time (as in, wall-clock), and plenty of times when you don't care when something computes as long as you end up getting a result at some point.

Yes, but that should be call-time distinction, not a function declaration distinction. This is briefly mentioned at the end of the linked article.

Edit: as other poster mentioned, async/await and promises also don't help with precise wall-clock time but that is entirely different matter.

You don't get reliable wall clock time unless you're working in RTOS. In a threaded OS everything in userland is async to an extent. In this school of thought, having to specify that something should be async manually could be seen as a failure of the language.

on recent good hardware there is no problem being around 1ms accuracy.

>That's essentially the main reason Node is any faster than Python.

v8's JIT is many times faster than Python in CPU bound tasks without any asynchronicity involved.

Python also has async/await