Run results for: single for loop vs multiple for loops for iterating over arrays

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:133.0) Gecko/20100101 Firefox/133.0

Browser: Firefox 133

Operating system: Windows

Device Platform: Desktop

Date tested: one year ago

single loop (small N)

656K/s

separate loops (small N)

560K/s

separate loops (big N)

326/s

single loop (big N)

317/s

View exact numbers

Test name	Executions per second
✓ single loop (small N)	655,928 Ops/sec
separate loops (small N)	559,504 Ops/sec
separate loops (big N)	326 Ops/sec
single loop (big N)	317 Ops/sec

Script Preparation code:

const smallN = 2 ** 10
const bigN = 2 ** 20

const arr1 = []
const arr2 = []

for (let i = 0; i < bigN; ++i) {
	arr1.push(Math.random())
	arr2.push(Math.random())
}

Tests:

single loop (big N)
for (let i = 0; i < bigN; ++i) { arr1[i] *= 2 arr2[i] *= 2 }
separate loops (big N)
for (let i = 0; i < bigN; ++i) arr1[i] *= 2 for (let i = 0; i < bigN; ++i) arr2[i] *= 2
single loop (small N)
for (let i = 0; i < smallN; ++i) { arr1[i] *= 2 arr2[i] *= 2 }
separate loops (small N)
for (let i = 0; i < smallN; ++i) arr1[i] *= 2 for (let i = 0; i < smallN; ++i) arr2[i] *= 2