You should do some measurement before calling it an improvement. If you read the ECMAScript standard[1] or this blog post from V8[2] about the inner workings of the `await` keyword, you would know even if you `await` a non-Promise value, it would still create a new Promise and put the suspended routine onto the microtask queue. So the change you made won't make a difference.

Besides, there is a JavaScript language feature that can give you finer control on routine suspension and resumption, decoupled from any of the microtask or macrotask queue. It's called the generator function. There are some good coroutine libraries based on generator functions, e.g. co.js[3] and redux-saga[4]. You can easily make something similar that can resume the suspended routine according to your scheduling policy that prioritize main thread rendering.

[1]: https://tc39.es/ecma262/#sec-promise-executor [2]: https://v8.dev/blog/fast-async#await-under-the-hood [3]: https://github.com/tj/co [4]: https://redux-saga.js.org