Performance of for-of given an array vs a generator

array-vs-generator-perf.js

function getNumberArray(maxValue) {
    const a = [];
	let i = 0
    for (i = 0; i < maxValue; i++) {
        a.push(i);
    }

    return a;
}

function* getNumberGenerator(maxValue) {
	let i = 0;
    for (i = 0; i < maxValue; i++) {
        yield i;
    }
}

function formatNumbers(strings, ...values) {
    let result = "";

    for (var i = 0; i < strings.length; i++) {
        result += strings[i];
        
        if (i < values.length) {
            if (typeof values[i] === "number") {
                result += formatNumber(values[i]);
            }
            else {
                result += values[i];
            }
        }
    }

    return result;
}

function formatNumber(x) {
    return x.toString().replace(/\B(?=(\d{3})+(?!\d))/g, ",");
}

function runTest(testName, numIterations, funcToTest) {
    console.log(`Running ${testName}...`);
    let dummyCalculation;
    const startTime = Date.now();
    const initialMemory = process.memoryUsage();
    const iterator = funcToTest(numIterations);

    for (let val of iterator) {
        dummyCalculation = numIterations - val;
    }

    const finalMemory = process.memoryUsage();

    // note: formatNumbers can be found here: https://jsfiddle.net/onz1ozjq/
    console.log(formatNumbers `Total time: ${Date.now() - startTime}ms`);
    console.log(formatNumbers `Rss:        ${finalMemory.rss - initialMemory.rss}`);
    console.log(formatNumbers `Heap Total: ${finalMemory.heapTotal - initialMemory.heapTotal}`);
    console.log(formatNumbers `Heap Used:  ${finalMemory.heapUsed - initialMemory.heapUsed}`);
}

runTest("Array",     100000000, getNumberArray)
runTest("Generator", 100000000, getNumberGenerator)

Results on my machine

Running Array...
Total time: 4,022ms
Rss: 2,728,939,520
Heap Total: 2,726,199,296
Heap Used: 2,704,236,368

Running Generator...
Total time: 2,541ms
Rss: 851,968
Heap Total: 0
Heap Used: -5,073,968