See my comment below: <a href="https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=11564354" rel="nofollow">https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=11564354</a><p>It&#x27;s not so simple as (paraphrasing) &#x27;ES6 is sugar and makes ES5 regress in speed.&#x27; Generally, &quot;make it work right, then make it work fast&quot; is actually a pretty good strategy for implementing new features.