This is a case of &quot;make it work right; then make it work fast&quot;. ES2015 performance will improve with time (we&#x27;ve already made 8-10x improvements on certain features) [0].<p>Strong mode work was stopped for a variety of nuanced reasons detailed here [1].<p>(Disclaimer: I&#x27;m a PM on the V8 team.)<p>[0]: <a href="https:&#x2F;&#x2F;twitter.com&#x2F;addyosmani&#x2F;status&#x2F;699976753255751681" rel="nofollow">https:&#x2F;&#x2F;twitter.com&#x2F;addyosmani&#x2F;status&#x2F;699976753255751681</a>
[1]: <a href="https:&#x2F;&#x2F;groups.google.com&#x2F;forum&#x2F;#!topic&#x2F;strengthen-js&#x2F;ojj3TDxbHpQ" rel="nofollow">https:&#x2F;&#x2F;groups.google.com&#x2F;forum&#x2F;#!topic&#x2F;strengthen-js&#x2F;ojj3TD...</a>