Speed Optimization | Web Training Wheels

Reduce unused JavaScript in WordPress

Audience: Developers, Intermediate
Speed Optimization

Most WordPress site owners will see the recommendation to “reduce unused Javascript” when they run a PageSpeed test.

The technically complete solution is out of reach for most site owners, but there is an effective shortcut solution for reducing unused JavaScript on your WordPress site that I share below.

What does “reduce unused JavaScript” mean?

JavaScript (JS) is a type of code used on website mostly for interactive elements like sliders, animations etc. Compared to CSS or images, it is much more resource intensive so it takes longer to process when your page is loading. It’s especially bad for mobile performance.

For best performance, you should aim to have as little JavaScript as possible on your site.

Loading JavaScript that isn’t even used on the page is a waste of resources and processing power, and that’s what this PageSpeed recommendation is getting at.

Audience: Consultants, Intermediate
Speed Optimization

If you’ve ever run a PageSpeed or other speed test for the mobile version of your site, you’ve undoubtedly been horrified by the low speed and score compared to the desktop version of your site.

In this post I’ll explain:

Why mobile performance is typically worse
The primary cause of slow mobile pages
How to create mobile-specific versions of your pages
How to remove unnecessary files from your mobile pages

Optimizing for mobile does take a bit of extra effort since site owners are usually “retrofitting” their sites for mobile performance.

If you are starting a new site, it will be easier if you consider mobile performance from the start, and make it a priority.

Audience: Beginners, Consultants, Intermediate
Speed Optimization

If you are using Google PageSpeed Insights to test your WordPress site, you’ll see this “avoid enormous network payloads” warning if the total size of your page is more than 1.6MB.

It sounds technical, but this is actually one of the recommendations that you as the site owner have the most control over. Unlike some PageSpeed recommendations, you can fix this one!

Speed Optimization

Core Web Vitals are the 3 key metrics that Google believes indicate healthy performance for your web site.

Whether you agree with their selection of metrics or not, soon you will not really have a choice.

Unlike their previous PageSpeed metrics, which did not impact ranking at all, Core Web Vitals will eventually be used as a ranking signal.

Today, we’re building on this work and providing an early look at an upcoming Search ranking change that incorporates these page experience metrics. We will introduce a new signal that combines Core Web Vitals with our existing signals for page experience to provide a holistic picture of the quality of a user’s experience on a web page.
https://webmasters.googleblog.com/2020/05/evaluating-page-experience.html

Audience: Developers, Intermediate
Speed Optimization

Last Updated on August 6, 2022.

Preload key requests is an “opportunity” that you may see recommended by PageSpeed.

What triggers this message?

PageSpeed will show you this message when there are necessary files to render (display) your page which are referred to 3 levels deep in your code.

Audience: Beginners, Developers, Intermediate
Speed Optimization

This is the blog post that accompanies a talk I gave at WordCamp Seattle in 2019. You can see the slides here. The video of the talk is up on WordPress.tv

Additionally, the HTTP Archive Web A l manac was published around the same time so I’ve also interspersed some of the insights from that report since they dovetail really nicely.

Providing excellent context for this post, the CMS chapter shows how sites built with a Content Management System (and WordPress sites comprise almost 75% of those in the report) tend to:

be more bloated with heavier page weights
use more 3rd party resources
use heavier images

Additionally it reported that WordPress sites tend to have slower performance metrics.

Now this is not really the fault of WordPress itself, it’s really due to what we site owners have done.

While it’s possible to build bloated pages and use techniques to make them seem fast, that shouldn’t be the goal. Let’s just build lighter pages to begin with!