I’ve been working recently to improve mobile speed on my websites. I have good quick hosting with WP Engine. I use Autoptimize which helps with the Javascript and CSS minimization. My desktop scores are good. Divi has a cumulative layout shift issue, which the developers are working on. I’ve chosen not to implement workarounds for that right now.
But my mobile scores needed some work. I had a score of 23 with PageSpeed Insights and a time of 5.6 seconds with GT Metrix.
I read recommendations for the PerfMatters plugin. It allows you to disable the loading of parts of the theme and plugin per page. My website is very simple. I disabled these modules in PerfMatters with no loss of functionality: Disable Emojis, Disable Embeds, Disable XML-RPC, Remove jQuery Migrate, Dashicons, Google Maps and Comments.
For my website home page, used the PerfMatters plugin to not load the modules relating to the Contact Form 7 payment form. I also turned off the Divi divi-custom-script module, the dash icons and others. If you disable too much in PerfMatters, you get a very odd looking website with no menu or structure. So some experiments did not go well. My mobile menu no longer worked because it needs the divi-custom-script module.
So I tried WP Rocket instead of autoptimize. I updated Divi to the latest version also. Got 66/98 in my last test.
Imagely was recommended to move my images into .webp formats. It did not work automatically on the Divi backgrounds, so this is tabled for now.
I worked to create these same results on https://backyardrotisserie.com, which is a legacy website hosted on goDaddy. I started with Page Speed Insights of 60 / 87.
With the installation and setup of PerfMatters, I got to 61/94 on the home page. Unfortunately, both the large jquery-core and divi-custom-script are needed for the mobile menu to work.
Still using PerfMatters, I added WP Rocket and disabled Leverage Browser Caching. I hit my best score yet 80 / 100 when goDaddy cooperated with some fast server responses.
If I wanted to speed this website up further, I would move it off goDaddy and onto faster hosting.