Slow website performance might be something that deprives your website of being ranked higher by search engines. That is also something that discourages customers to stay on your website longer than 3-4 seconds if it isn't loading.

This module allows you to enable the JavaScript loading on your website, moving JS to the bottom of the page which significantly reduced the loading time.

Follow the link in order to learn more about the Magento 2 Rocket JavaScript / Deferred JavaScript

Source by Magento 2 Extensions