Updated Nov 22, 2025. It’s been well over a year and a half since this article was initially written. Lately, I’ve allocated a lot of time trying to optimize my site and increase my mobile page speed score, so I thought that I would revisit this article and make some adjustments, and also mention the improvements seen by adding Perfmatters into the mix.
If you’re using the Astra WordPress theme and hosting your website on Siteground, there’s a chance that you might have experienced issues with the caching configuration or your Astra theme randomly no longer displaying as it should, which was the main issue that sent me down this rabbit hole.
Astra Theme Styles Display Randomly Breaks
Oftentimes, I would check my site and everything would look fine. Then, for an unknown reason it would randomly not render properly. It seemed like there was no rhyme or reason why the display would all of the sudden break.
To fix this, the problem seemed to actually lay within an Astra theme setting conflicting with my setup. By going to the Astra Dashboard and disabling File Generation in the Astra General Settings, it fixed the random display issues that would make my site appear broken.
Fixing the display problems was great, but it didn’t address the fact that my website’s mobile speed performance would benefit from proper caching, but at the time I didn’t have the bandwidth to troubleshoot it further and decided that I would address the problem later.
Improving my mobile page speed was always on my list to fix, especially since Google weighs your website’s performance in search engine results ranking and my mobile Perfomance score was in the 60s, with the remainder consistently in the 90s.
Well, I finally had a chance to set some time aside to increase my page speed score. The following information is a general overview of what ended up working for me to get my mobile page speed insight score up into the mid 90s with the help of Perfmatters and lots of patience.
That’s not to say that I have everything all figured out, as I’m sure I probably only scratched the surface and there’s still plenty of room to further optimize.
tip. If there’s on thing to remember throughout the setup process, you don’t want two different services or plugins performing the same tasks.
Here’s how I ended up configuring my Siteground Speed Optimizer cache settings to work with Perfmatters.
1. Configure Siteground Server Cache
Siteground automatically installs two plugins to WordPress sites hosted on their servers. The Speed Optimizer plugin is what handles your website cache. The other one that’s automatically installed is Security Optimizer. In this article we’re going to focus on the Speed Optimizer plugin.
Before getting into the configuration of the Speed Optimizer plugin, take a look at your Siteground hosting environment and make sure that NGINX Direct Delivery and Memcached are both turned on. Dynamic Cache is turned on by default and can be managed within the WordPress plugin.
2. Configure the Speed Optimizer Plugin Caching Settings
Log into the WordPress Dashboard to configure Siteground’s Speed Optimizer plugin. If Speed Optimizer is not yet enabled, navigate to Plugins, install it if it isn’t already, then activate it.
Next, go to Speed Optimizer > Caching and disable File-Based Caching and Dynamic Caching, leaving Memcached enabled.
After lots of testing and cache clearing, I’ve figured out that with Perfmatters and Dynamic Caching both turned on, Dynamic Caching would cache the first load of my site – whether it was mobile or desktop loaded first – and then would prioritize those styles for each additional page load without consideration of the device size and breakpoint.
One thing that took a while to figure out and nearly drove me mad, was that if I cleared my server cache and refreshed the site at a mobile sized breakpoint it would look perfect, but when I checked the desktop display I would see a white flash of the drop down menu because the mobile styles were being prioritized.
The same scenario would happen on the flip-side too, if I loaded a desktop version of the site first after clearing the server cache and then tried checking the mobile display second, I would see desktop styles spilling into the mobile display and the layout would adjust sizing as the code loaded and was available for the browser to parse.
Disabling the Dynamic Caching feature solved this issue for me, but your mileage may vary.
3. Configure the Speed Optimizer CSS Settings
Next, go to Speed Optimizer > Frontend Optimization and turn on Minify CSS Files, leaving all of the other items disabled.
4. Configure the Speed Optimizer JavaScript Settings
With the CSS settings now in place, let’s take a look at the frontend Javascript settings.
5. Configure the Speed Optimizer General Settings
Once my JavaScript settings were updated I went into the General tab and configured my settings as shown below.
tip. While editing and testing your cache settings, view your website in an Incognito or Private browser window so the site loads without the Administrator Dashboard getting in the way and adding unnecessary bloat to the test results.
6. Configure Perfmatters for Astra WordPress Theme on Siteground
After turning off a number of services in the Speed Optimizer plugin, I turned my attention to Perfmatters. I’ve tried a number of caching plugins, and I have to say that this one was the most straightforward and easiest to implement. It has an intuitive UI, documentation links next to each setting, and lots of video tutorials that can found on the web.
Depending on your site requirements you might find that you need to adjust your settings accordingly. It’s also worth noting, I use Astra to load fonts locally, so I didn’t turn this feature on in the general settings of Perfmatters.
Without extensively going into the details, below is what worked for me and where my settings currently stand. I’m by far an expert, so don’t take this as a definitive guide.
tip. While setting up Perfmatters, be sure to clear your cache in the following order and test after making each change, since edits can possibly conflict or break features of your site:
1. Perfmatters (Clear Unused CSS & Clear Minified JS & CSS)
2. Purge SG Cache (Siteground)
3. Refresh your website while viewing in Incognito
4. Run a page speed test
5. Repeat (over, and over, and over)
Here’s a video that I found very helpful while trying to setup Perfmatters.
If you’re experiencing caching issues while using Siteground’s Speed Optimizer plugin with an Astra theme, consider adjusting the settings mentioned above and consider a plugin like Perfmatters. These tweaks could potentially resolve any caching issues and simultaneously enhance the speed of your website.
