Run results for: Intl.NumberFormat cache vs new Intl.NumberFormat vs toLocaleString currency

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:132.0) Gecko/20100101 Firefox/132.0

Browser: Firefox 132

Operating system: Windows

Device Platform: Desktop

Date tested: one year ago

cached Intl.NumberFormat instance

1.6M/s

new Intl.NumberFormat

66K/s

Number.prototype.toLocaleString

59K/s

View exact numbers

Test name	Executions per second
✓ cached Intl.NumberFormat instance	1,633,938 Ops/sec
new Intl.NumberFormat	65,560 Ops/sec
Number.prototype.toLocaleString	59,421 Ops/sec

Script Preparation code:

window.formatCache = new Map();
window.formatNumber = function(value, options) {
  var key = JSON.stringify(options);
  var formatter = window.formatCache.get(key);
  if (!formatter) {
    formatter = new Intl.NumberFormat(options.locale, options);
    window.formatCache.set(key, formatter);
  }
  return formatter.format(value);
};

Tests:

cached Intl.NumberFormat instance
window.formatNumber(3_950_219.56, { locale:'pt-BR', style: 'currency', currency: 'BRL' });
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' });