Date.toLocaleString slowdown since 3.52.2

[msvab]

What

We've noticed that Date.toLocaleString() has great performance degradation on IE11 since version 3.53.2. 3.53.1 is the most recent version which works fine.

Details

Attached is a very basic HTML page which shows the problem. Using version 3.53.1 the benchmark takes 157ms, but on 3.53.2 it takes 6400ms. We use this function to render dates on a datepicker and users with less powerful computers see the "page is not responding due to a long-running script" error.

test.zip

I'm happy to provide more details or if you can point me to the right direction to narrow this issue further?

[romainmenke]

@msvab Could you maybe create a repo with the contents of that zip? Not really best practice to download and open unknown zips :D

[romainmenke]

confirmed :

code : https://github.com/romainmenke/intl-performance-issue-1 hosted : https://romainmenke.github.io/intl-performance-issue-1/

This code was run a 100 times in the reproduction

for (var i = 0; i < 100; i++) {
	var event = new Date(Date.UTC(2012, 11, 20, 3, 0, 0));
	event.toLocaleString('es', { timeZone: 'UTC' });
}

---

@longlho Can you take a look?

[longlho]

hmm what about latest version? Those are super old versions that don't use @formatjs/intl-datetimeformat so I don't have much control over it

[msvab]

hmm what about latest version? Those are super old versions that don't use @formatjs/intl-datetimeformat so I don't have much control over it

@longlho The latest version 3.104.0 is actually the one where we discovered the slowdown. Then we went back to identify which was the last version with acceptable speed.

[romainmenke]

https://github.com/Financial-Times/polyfill-library/compare/v3.53.2..v3.53.1

~~Maybe it's not a change in an Intl polyfill, but something in a dependency, or the build output?~~

To me this is starting to look like 3.53.2 fixed the build process which caused all needed polyfills to be loaded. 3.53.1 is most likely faster because it is not really working.

---

polyfill list from 3.53.1

 * Features requested: Intl.DateTimeFormat,Intl.DateTimeFormat.~locale.es,Intl.NumberFormat.~locale.es,Intl.PluralRules.~locale.es
 * 
 * - Intl, License: MIT (required by "Intl.PluralRules.~locale.es", "Intl.PluralRules")
 * - Intl.PluralRules, License: MIT (required by "Intl.PluralRules.~locale.es")
 * - Intl.PluralRules.~locale.es, License: MIT */

---

polyfill list from 3.53.2

 * Features requested: Intl.DateTimeFormat,Intl.DateTimeFormat.~locale.es,Intl.NumberFormat.~locale.es,Intl.PluralRules.~locale.es
 * 
 * - _ESAbstract.Call, License: CC0 (required by "Intl.NumberFormat.~locale.es", "Intl.NumberFormat", "Object.setPrototypeOf", "Object.getOwnPropertyDescriptor", "_ESAbstract.ToPropertyKey", "_ESAbstract.ToPrimitive", "_ESAbstract.OrdinaryToPrimitive")
 * - _ESAbstract.CreateDataProperty, License: CC0 (required by "Intl.PluralRules.~locale.es", "Intl.Locale", "Set", "_ESAbstract.CreateIterResultObject")
 * - _ESAbstract.CreateMethodProperty, License: CC0 (required by "Intl.NumberFormat.~locale.es", "Intl.NumberFormat", "Object.setPrototypeOf", "Object.getOwnPropertyNames", "Array.prototype.includes")
 * - _ESAbstract.Get, License: CC0 (required by "Intl.NumberFormat.~locale.es", "Intl.NumberFormat", "Object.setPrototypeOf", "Object.getOwnPropertyDescriptor", "_ESAbstract.ToPropertyKey", "_ESAbstract.ToPrimitive", "_ESAbstract.OrdinaryToPrimitive")
 * - _ESAbstract.HasOwnProperty, License: CC0 (required by "Intl.NumberFormat.~locale.es", "Intl.NumberFormat", "Object.setPrototypeOf", "Object.getOwnPropertyDescriptor")
 * - _ESAbstract.IsArray, License: CC0 (required by "Intl.NumberFormat.~locale.es", "Intl.NumberFormat", "WeakMap")
 * - _ESAbstract.IsCallable, License: CC0 (required by "Intl.NumberFormat.~locale.es", "Intl.NumberFormat", "Object.setPrototypeOf", "Object.getOwnPropertyDescriptor", "_ESAbstract.ToPropertyKey", "_ESAbstract.ToPrimitive", "_ESAbstract.OrdinaryToPrimitive")
 * - _ESAbstract.SameValueNonNumber, License: CC0 (required by "Intl.NumberFormat.~locale.es", "Intl.NumberFormat", "WeakMap", "_ESAbstract.SameValue")
 * - _ESAbstract.ToBoolean, License: CC0 (required by "Intl.PluralRules.~locale.es", "Intl.Locale", "Set", "_ESAbstract.IteratorComplete")
 * - _ESAbstract.ToObject, License: CC0 (required by "Intl.NumberFormat.~locale.es", "Intl.NumberFormat", "WeakMap", "_ESAbstract.GetIterator", "_ESAbstract.GetV")
 * - _ESAbstract.GetV, License: CC0 (required by "Intl.NumberFormat.~locale.es", "Intl.NumberFormat", "WeakMap", "_ESAbstract.GetIterator")
 * - _ESAbstract.GetMethod, License: CC0 (required by "Intl.NumberFormat.~locale.es", "Intl.NumberFormat", "Object.setPrototypeOf", "Object.getOwnPropertyDescriptor", "_ESAbstract.ToPropertyKey", "_ESAbstract.ToPrimitive")
 * - _ESAbstract.Type, License: CC0 (required by "Intl.NumberFormat.~locale.es", "Intl.NumberFormat", "Object.setPrototypeOf", "Object.getOwnPropertyDescriptor", "_ESAbstract.ToPropertyKey", "_ESAbstract.ToPrimitive", "_ESAbstract.OrdinaryToPrimitive")
 * - _ESAbstract.CreateIterResultObject, License: CC0 (required by "Intl.PluralRules.~locale.es", "Intl.Locale", "Set")
 * - _ESAbstract.GetPrototypeFromConstructor, License: CC0 (required by "Intl.NumberFormat.~locale.es", "Intl.NumberFormat", "WeakMap", "_ESAbstract.OrdinaryCreateFromConstructor")
 * - _ESAbstract.OrdinaryCreateFromConstructor, License: CC0 (required by "Intl.NumberFormat.~locale.es", "Intl.NumberFormat", "WeakMap")
 * - _ESAbstract.IteratorClose, License: CC0 (required by "Intl.NumberFormat.~locale.es", "Intl.NumberFormat", "WeakMap")
 * - _ESAbstract.IteratorComplete, License: CC0 (required by "Intl.NumberFormat.~locale.es", "Intl.NumberFormat", "WeakMap", "_ESAbstract.IteratorStep")
 * - _ESAbstract.IteratorNext, License: CC0 (required by "Intl.NumberFormat.~locale.es", "Intl.NumberFormat", "WeakMap", "_ESAbstract.IteratorStep")
 * - _ESAbstract.IteratorStep, License: CC0 (required by "Intl.NumberFormat.~locale.es", "Intl.NumberFormat", "WeakMap")
 * - _ESAbstract.IteratorValue, License: CC0 (required by "Intl.NumberFormat.~locale.es", "Intl.NumberFormat", "WeakMap")
 * - _ESAbstract.OrdinaryToPrimitive, License: CC0 (required by "Intl.NumberFormat.~locale.es", "Intl.NumberFormat", "Object.setPrototypeOf", "Object.getOwnPropertyDescriptor", "_ESAbstract.ToPropertyKey", "_ESAbstract.ToPrimitive")
 * - _ESAbstract.SameValue, License: CC0 (required by "Intl.NumberFormat.~locale.es", "Intl.NumberFormat", "WeakMap")
 * - _ESAbstract.SameValueZero, License: CC0 (required by "Intl.NumberFormat.~locale.es", "Intl.NumberFormat", "Object.setPrototypeOf", "Object.getOwnPropertyNames", "Array.prototype.includes")
 * - _ESAbstract.ToInteger, License: CC0 (required by "Intl.NumberFormat.~locale.es", "Intl.NumberFormat", "Object.setPrototypeOf", "Object.getOwnPropertyNames", "Array.prototype.includes", "_ESAbstract.ToLength")
 * - _ESAbstract.ToLength, License: CC0 (required by "Intl.NumberFormat.~locale.es", "Intl.NumberFormat", "Object.setPrototypeOf", "Object.getOwnPropertyNames", "Array.prototype.includes")
 * - _ESAbstract.ToPrimitive, License: CC0 (required by "Intl.NumberFormat.~locale.es", "Intl.NumberFormat", "Object.setPrototypeOf", "Object.getOwnPropertyNames", "Array.prototype.includes", "_ESAbstract.ToString")
 * - _ESAbstract.ToString, License: CC0 (required by "Intl.NumberFormat.~locale.es", "Intl.NumberFormat", "Object.setPrototypeOf", "Object.getOwnPropertyNames", "Array.prototype.includes")
 * - _ESAbstract.ToPropertyKey, License: CC0 (required by "Intl.NumberFormat.~locale.es", "Intl.NumberFormat", "Object.setPrototypeOf", "Object.getOwnPropertyDescriptor")
 * - Array.prototype.includes, License: MIT (required by "Intl.NumberFormat.~locale.es", "Intl.NumberFormat", "Object.setPrototypeOf", "Object.getOwnPropertyNames")
 * - Array.prototype.sort, License: MIT (required by "Intl.PluralRules.~locale.es", "Intl.Locale")
 * - Object.getOwnPropertyDescriptor, License: CC0 (required by "Intl.NumberFormat.~locale.es", "Intl.NumberFormat", "WeakMap", "Symbol")
 * - Object.keys, License: MIT (required by "Intl.NumberFormat.~locale.es", "Intl.NumberFormat", "WeakMap", "Symbol")
 * - Object.assign, License: CC0 (required by "Intl.NumberFormat.~locale.es", "Intl.NumberFormat", "Intl.PluralRules")
 * - Intl.getCanonicalLocales, License: MIT (required by "Intl.NumberFormat.~locale.es", "Intl.NumberFormat", "Intl.PluralRules")
 * - Object.getOwnPropertyNames, License: CC0 (required by "Intl.NumberFormat.~locale.es", "Intl.NumberFormat", "WeakMap", "Symbol")
 * - Object.setPrototypeOf, License: MIT (required by "Intl.NumberFormat.~locale.es", "Intl.NumberFormat", "Intl.PluralRules")
 * - Symbol, License: MIT (required by "Intl.NumberFormat.~locale.es", "Intl.NumberFormat", "WeakMap", "Symbol.toStringTag")
 * - Symbol.iterator, License: MIT (required by "Intl.NumberFormat.~locale.es", "Intl.NumberFormat", "WeakMap", "_ESAbstract.GetIterator")
 * - _ESAbstract.GetIterator, License: CC0 (required by "Intl.NumberFormat.~locale.es", "Intl.NumberFormat", "WeakMap")
 * - Symbol.species, License: MIT (required by "Intl.PluralRules.~locale.es", "Intl.Locale", "Set")
 * - Set, License: CC0 (required by "Intl.PluralRules.~locale.es", "Intl.Locale")
 * - Symbol.toStringTag, License: MIT (required by "Intl.NumberFormat.~locale.es", "Intl.NumberFormat", "WeakMap")
 * - WeakMap, License: MIT (required by "Intl.NumberFormat.~locale.es", "Intl.NumberFormat", "Intl.PluralRules")
 * - Intl.Locale, License: MIT (required by "Intl.NumberFormat.~locale.es", "Intl.NumberFormat", "Intl.PluralRules")
 * - Intl.PluralRules, License: MIT (required by "Intl.NumberFormat.~locale.es", "Intl.NumberFormat")
 * - Intl.NumberFormat, License: MIT (required by "Intl.NumberFormat.~locale.es")
 * - Intl.DateTimeFormat, License: MIT (required by "Intl.DateTimeFormat.~locale.es")
 * - Intl.DateTimeFormat.~locale.es, License: MIT
 * - Intl.NumberFormat.~locale.es, License: MIT
 * - Intl.PluralRules.~locale.es, License: MIT */