Await Performance

measure-await.js

async function queueAlways() {

    let x;

    for (let i = 0; i < 100000; ++i)
        x = await i;
}

async function queueIf() {

    let x;

    for (let i = 0; i < 100000; ++i)
        x = ("then" in Object(i) ? await i : i);
}

async function time(fn) {

    let ts = +new Date;
    await fn();
    return (+new Date) - ts;
}

export async function main() {

    let time1 = await time(queueAlways),
        time2 = await time(queueIf);

    console.log(`Conditional: ${ time2 }ms`);
    console.log(`Always: ${ time1 }ms (${ (time1 / time2).toFixed(0) }x slower)`);
}

/*

Running with es6now 0.8.10 (Node v0.11.13 --harmony)

Conditional: 35ms
Always: 941ms (27x slower)

*/