Defer JavaScript means that JavaScript files loading will be delayed until parsing the page content finishes. Therefore, a browser loads all content before JavaScript files, which makes Magento sites perform faster than loading everything at the same time.
Beside deferring JavaScript manually by changing codes, admin can install an extension also called Defer JavaScript to improve site speed and enhance customer experience effectively.

- Delay JavaScript files loading till the last moment when the browser finishes loading HTML and CSS

- Effectively defer Iframes loading

- Improve page speed score when testing with GTMetrix

+ After installing Defer JavaScript:

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+ Before installing Defer JavaScript:

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Check it out for FREE Installation - FREE 1-year Support and FREE Updates!

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