For maximum page speed results, use it together with a caching plugin

As for the loaded JavaScript files, attributes such as defer and async can be applied

There are a plethora of techniques that are often used to defer parsing; however, the simple and preferred technique is to simply Defer loading of JavaScript until it is needed. If this technique isn’t appropriate to use on your page, it is next suggested that you use the <script async> attribute where appropriate, which prevents parsing from blocking the initial page load by deferring it until the browser’s UI thread is not busy doing something else. All these settings can be applied with Asset CleanUp Pro without writing any code.

Change the location of the CSS/JS files (could be moved from HEAD to BODY to prevent render-blocking or vice-versa if you need early triggering of specific files)

Unload CSS/JS that is hardcoded (not loaded via the standard WordPress functions such as wp_enqueue_scripts()). The LINK/STYLE/SCRIPT tags could have been added via editing the PHP code (not using the right WordPress action hooks), directly inside posts content, widgets, or via plugins such as “Insert Headers and Footers”, “Head, Footer and Post Injections”, etc.

Test Mode” Functionality → Worried about making optimization mistakes? Don’t be anymore!

This allows you to optimize the website (unload useless files, set async, defer to loaded JavaScript files, clean up HTML code) without applying the changes “live” (to the regular visitor) in case you ever have any doubts that a change could break the functionality of the page/website. Any changes you’ve done will only be applied to you (the logged-in administrator). Once you’re happy with how the page looks and works, you can disable “Test Mode” to push the changes live so everyone else can enjoy the faster page loads