Performance comparison between different for-loop variations and payload sizes

foreach.ts

import { FORMAT_MD, suite } from "@thi.ng/bench";
import { range } from "@thi.ng/transducers";

const testForIndexFwd = (src: number[]) => {
    let m = 0;
    for (let i = 0, n = src.length; i < n; i++) m += src[i];
    return m;
};

const testForIndexRev = (src: number[]) => {
    let m = 0;
    for (let i = src.length; i-- > 0; ) m += src[i];
    return m;
};

const testForOf = (src: number[]) => {
    let m = 0;
    for (let x of src) m += x;
    return m;
};

const testForIter = (src: number[]) => {
    let m = 0;
    let x: IteratorResult<number>;
    const iter = src[Symbol.iterator]();
    while (!(x = iter.next()).done) m += x.value;
    return m;
};

const testForEach = (src: number[]) => {
    let m = 0;
    src.forEach((x) => (m += x));
    return m;
};

for (let [n, size] of [
    [1e1, 1e5],
    [1e2, 1e4],
    [1e3, 1e3],
    [1e4, 1e2],
    [1e5, 10],
    [1e6, 10],
]) {
    const src = [...range(n)];
    const nf = n.toExponential(0);
    suite(
        [
            { title: `for-fwd (${nf})`, fn: () => testForIndexFwd(src) },
            { title: `for-rev (${nf})`, fn: () => testForIndexRev(src) },
            { title: `for-of (${nf})`, fn: () => testForOf(src) },
            { title: `for-iter (${nf})`, fn: () => testForIter(src) },
            { title: `for-each (${nf})`, fn: () => testForEach(src) },
        ],
        {
            size,
            iter: 1e3,
            warmup: 1e3,
            format: FORMAT_MD,
        }
    );
    console.log("\n");
}

results.md

The for-each version is consistently the worst performing option (between ~1.5x - 5.7x(!) slower than a classic for-loop)

Title	Iter	Size	Total	Mean	Median	Min	Max	Q1	Q3	SD%
for-fwd (1e+1)	1000	100000	771.13	0.77	0.77	0.76	0.92	0.76	0.78	1.29
for-rev (1e+1)	1000	100000	1259.20	1.26	1.26	1.24	1.45	1.25	1.27	1.13
for-of (1e+1)	1000	100000	1147.50	1.15	1.15	1.12	1.35	1.15	1.15	0.94
for-iter (1e+1)	1000	100000	1395.20	1.40	1.40	1.37	2.08	1.38	1.40	2.85
for-each (1e+1)	1000	100000	1976.61	1.98	1.96	1.91	2.48	1.94	1.99	2.94

Title	Iter	Size	Total	Mean	Median	Min	Max	Q1	Q3	SD%
for-fwd (1e+2)	1000	10000	692.66	0.69	0.69	0.69	0.80	0.69	0.69	1.04
for-rev (1e+2)	1000	10000	1100.71	1.10	1.09	1.06	1.54	1.08	1.11	2.83
for-of (1e+2)	1000	10000	938.84	0.94	0.94	0.92	0.98	0.93	0.94	0.88
for-iter (1e+2)	1000	10000	1073.34	1.07	1.07	1.05	1.31	1.05	1.08	1.88
for-each (1e+2)	1000	10000	1020.69	1.02	1.02	0.95	1.11	1.02	1.03	1.41

Title	Iter	Size	Total	Mean	Median	Min	Max	Q1	Q3	SD%
for-fwd (1e+3)	1000	1000	649.24	0.65	0.65	0.64	0.67	0.65	0.65	0.70
for-rev (1e+3)	1000	1000	964.99	0.96	0.97	0.95	1.03	0.97	0.97	0.97
for-of (1e+3)	1000	1000	826.90	0.83	0.81	0.79	7.98	0.81	0.85	27.48
for-iter (1e+3)	1000	1000	965.97	0.97	0.97	0.95	1.00	0.97	0.97	0.66
for-each (1e+3)	1000	1000	1044.17	1.04	1.04	1.04	1.15	1.04	1.04	1.47

Title	Iter	Size	Total	Mean	Median	Min	Max	Q1	Q3	SD%
for-fwd (1e+4)	1000	100	637.23	0.64	0.64	0.63	0.66	0.64	0.64	0.54
for-rev (1e+4)	1000	100	955.42	0.96	0.96	0.94	1.01	0.96	0.96	1.17
for-of (1e+4)	1000	100	798.15	0.80	0.80	0.78	0.84	0.80	0.80	1.02
for-iter (1e+4)	1000	100	956.19	0.96	0.96	0.94	1.00	0.96	0.96	0.39
for-each (1e+4)	1000	100	1038.34	1.04	1.03	1.01	1.16	1.03	1.04	1.08

Title	Iter	Size	Total	Mean	Median	Min	Max	Q1	Q3	SD%
for-fwd (1e+5)	1000	10	959.51	0.96	0.96	0.94	1.19	0.95	0.96	1.75
for-rev (1e+5)	1000	10	961.61	0.96	0.96	0.94	1.14	0.95	0.96	1.49
for-of (1e+5)	1000	10	957.20	0.96	0.96	0.94	1.02	0.95	0.96	1.00
for-iter (1e+5)	1000	10	962.33	0.96	0.96	0.94	1.25	0.95	0.96	1.80
for-each (1e+5)	1000	10	5464.19	5.46	5.45	5.30	5.82	5.40	5.53	1.76

Title	Iter	Size	Total	Mean	Median	Min	Max	Q1	Q3	SD%
for-fwd (1e+6)	1000	10	9635.94	9.64	9.62	9.41	10.47	9.60	9.65	0.79
for-rev (1e+6)	1000	10	9676.22	9.68	9.61	9.54	10.84	9.59	9.73	1.42
for-of (1e+6)	1000	10	9657.31	9.66	9.62	9.58	12.48	9.59	9.67	1.59
for-iter (1e+6)	1000	10	9645.22	9.65	9.62	9.58	10.42	9.59	9.67	0.88
for-each (1e+6)	1000	10	45568.20	45.57	45.36	44.77	50.86	45.19	45.66	1.40