[performance] new Intl.NumberFormat is slow

[t2ym]

[performance] new Intl.NumberFormat is slow

Possible Fix

• Since new Intl.NumberFomrat is called with lang and options, observe these parameters and cache the new Intl.NumberFormat(lang, options) object for later usage
• The expected reliable caching algorithm is not as simple as expected with performance in consideration.

Notes

• Just calling .format() method is 100 times faster than instantiating Intl.NumberFormat on each call
• The fix priority is low since <i18n-number> should not be used so heavily

[t2ym]

Notes

• This fix is not ultimate but effective enough. The performance of render() is more than 13 times higher than the original.