Let’s consider a simple example. When a website visitor is on a fast 3G/slow 4G (standard recommendation for mobile throttling) network speed, navigates to a page they would not like to wait for all resources to load, which could be a few kilobytes to megabytes, and see nothing for a couple of seconds. Rather, the quick way to start engaging visitors is to show what piece of the content can be rendered as fast as possible, and in the background keep loading all other assets. The initial rendering also called First Contentful Paint (FCP) is one of six metrics tracked in the Core Web Vital (CWV) to determine the page experience and PageSpeed score.
As the elements are dependent on deferred assets, it can make the visitor’s experience worse by introducing more delay or even layout reflow (increased CLS) in some cases.
This is a good way to simulate optimized page loading behavior. Irrespective of whether you use RabbitLoader or not, these adjustments will improve visitors’ experience coming from a variety of network speeds and device processing power.
If you are using RabbitLoader, most probably there are already some page rules set up in advance to control the optimization behavior. If you are not familiar with it, please read about the page rules first.
Head on to Settings->Page Rules on the RabbitLoader account page. Click on the modify button for the page rule you want to modify. If you want this new setting to be effective for the entire website, choose the ‘*’ rule.
<script scr="my-imp-script.js" />
Should you wish to exclude only my-imp-script.js from being optimized or deferred loading, please add the JS file name in the Page Rule.
You can add multiple file names separated by a comma.
Note: JS files should be excluded with care. If the excluded file has a dependency on other JS files that are going to be deferred, it can break your website.