Run results for: What's faster? cached Intl.NumberFormat vs new Intl.NumberFormat vs toLocaleString currency

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/26.0.1 Safari/605.1.15

Browser: Safari 26

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: 9 months ago

cached Intl.NumberFormat instance

2.8M/s

Number.prototype.toLocaleString

34K/s

new Intl.NumberFormat

34K/s

View exact numbers

Test name	Executions per second
✓ cached Intl.NumberFormat instance	2,781,179 Ops/sec
Number.prototype.toLocaleString	33,896 Ops/sec
new Intl.NumberFormat	33,546 Ops/sec

Script Preparation code:

window.cachedFormatter = new Intl.NumberFormat('pt-BR', { style: 'currency', currency: 'BRL' });

Tests:

cached Intl.NumberFormat instance
window.cachedFormatter.format(3_950_219.56);
new Intl.NumberFormat
new Intl.NumberFormat('pt-BR', { style: 'currency', currency: 'BRL' }).format(3_950_219.56);
Number.prototype.toLocaleString
(3_950_219.56).toLocaleString('pt-BR', { style: 'currency', currency: 'BRL' });