Async/await overhead

async_await_microbenchmark.js

async function f(n) {
  if (n === 0 ) return Promise.resolve(1);;

  return await f(n-1);
} 

async function g(n) {
  if (n === 0 ) return Promise.resolve(1);

  return g(n-1);
} 

function h(n) {
  if (n === 0 ) return Promise.resolve(1);

  return h(n-1);
} 

async function caller(fn) {
  for(let i = 0; i<100000; i++) {
    await fn(1000);
  }
}

async function main() {
  let start;
  
  start = new Date();
  await caller(f);
  console.log(`N async + N await: ${new Date() - start} ms`);

  start = new Date();
  await caller(g);
  console.log(`N async + 1 await: ${new Date() - start} ms`);

  start = new Date();
  await caller(h);
  console.log(`1 async + 1 await: ${new Date() - start} ms`);
}

main();

results.md

❯ time node .vscode/async.js
N async + N await: 18228 ms
N async + 1 await: 6064 ms
1 async + 1 await: 434 ms
node .vscode/async.js  25.31s user 1.12s system 105% cpu 25.041 total