[Review] WP-Rocket + SG Optimizer : Does it Improve Page Speed Performance

To optimize the page speed for a WordPress site, WP-Rocket is suggested as the best cache plugin. I learnt on Google that it had many good features. In many of the reviews I read, it was giving the best score. I already was using SiteGround (SG) as web hosting.

The magic of SG is it’s default performance boosting plugin called SG Optimizer. I was very satisfied with its results. It supports GZIP compression, Browser caching, Minification of HTML, CSS, JS files, Combine CSS files, Image Optimization, Lazy Load Images etc. I am using CloudFlare free version for CDN along with SiteGround hosting service.

[wps_alert type=”primary”]But coming to page loading time in PageSpeed Insights (based on LightHouse engine of Google) mobile results, which is a crucial ranking signal for Google search results, it was giving very low score and high value.[/wps_alert]

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This seriously impacts the mobile traffic. Though I’m using an AMP plugin to better optimize for mobile search results, this factor was well below par.

SG Optimizer caching mechanism does a good job of loading your pages faster.

WordPress plugins used on the Site

[wps_note size=”17″ background=”#fae588″ color=”#333333″ radius=”3″] Active Plugins: Accelerated Mobile Pages, Ad Inserter, Akismet Anti-Spam, Classic Editor, Lightweight Subscribe To Comments, Contextual Related Posts, Cookie Notice, Easy Table of Contents, EWWW Image Optimizer, Inline Related Posts, kk Star Ratings, Link Juice Keeper, Redirection, Schema Creator by Raven, SG Optimizer, TablePress, Ultimate Category Excluder, Wordfence Security, Yoast SEO, WP Review Pro, WP Rocket, WP Shortcode Pro by MyThemeShop[/wps_note]

Does WP-Rocket Improve Mobile Page Loading Time

The Speed Index for mobile pages is very high with WP-Rocket plugin. The main reason is JavaScript (JS) payload. Google PageSpeed Insights indicates the following diagnostics –

  1. Minimize main thread work
  2. Reduce JavaScript execution time.

In the original test without WP-Rocket and with SG Optimizer plugin activated without Image Optimization (only Lazy Loading allowed), the mobile page speed was low.

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I sent a support request to the WP-Rocket team regarding my problem. I got the following answer.

Arun from WP Rocket here. Thank you for contacting WP Rocket support today.

There are many reasons why mobile is slower.

  • The CSS is loaded as render blocking for compatibility with AMP.
  • The test is conducted on a mobile device which often has slower processor than a desktop to process the JS and execute them.

If you expand the suggestion you will read the following:

Reduce JavaScript execution time – “Consider reducing the time spent parsing, compiling, and executing JS. You may find delivering smaller JS payloads helps with this”

Minimize main-thread work – “Consider reducing the time spent parsing, compiling and executing JS. You may find delivering smaller JS payloads helps with this.”

JS, once downloaded, has to be “read” and “understood” by the browser (parsed and compiled) and is then executed within the browser. The more JS there is, the more time the browser will need to parse, compile and execute it.

WP Rocket can help reduce the “size” of the JS file through minification, but minification does not reduce the “amount” of JS there is.

To reduce JS execution time you have to remove the JS that is not needed in the page by disabling plugin or theme JS files from loading on the page. This is custom development and cannot be automated by WP Rocket.

Here are few third party plugins that can help you remove unwanted JS from your pages. Please use them with care and consult your developer if you need help.

Best regards.

My Case-Study regarding WP-Rocket and Page Loading Time

I have selected 3 pages to test the efficiency of WP-Rocket + SG Optimizer combination on page load speed.

The pages were of different size having more than 10+ images, from the same website.

#1 Using PageSpeed Insights (Google tool)

Typical  test showed the following results of one of the pages.

In all the 3 tests, the mobile version had a very low score between 30 to 40.
The desktop version faired better between 70 to 85.

[wps_note size=”17″ background=”#eeee22″ color=”#333333″ radius=”3″]In May 2019, Google made it clear that mobile-indexing will be the first priority for all devices. In this context it is important, you have a low mobile page loading time.[/wps_note]

As mentioned before, there were several red marks in the PageSpeed lab data.

[wps_note size=”17″ background=”#fae588″ color=”#333333″ radius=”3″]Speed Index, First CPU Idle, Time to Interactive, Max Potential First Input Display were showing negative results, in-spite of using WP-Rocket.[/wps_note]

The above is the desktop score which is far better than mobile pagespeed value. Also, the speed factors are good compared to mobile. I don’t know the reason behind this, but desktop looks OK. You can see that except speed index, other factors are green.

#2 Using GTMetrix Page Speed Testing Tool

The PageSpeed Grade was high for all the 3 pages. It was above 90 with an A grade.
The YSlow Grade was showing C grade with a score of around 75.
It shows that all the pages were of size around 600KB.
The fully loaded time took between 2.8s to 3.5s.

The following were some of the parameters with a low grade or score in the PageSpeed test.
1. Leverage browser caching
2. Minimize request size

The YSlow score showed the following deficiences.
1. Add Expire headers
2. Reduce DNS lookups.
3. Use cookie-free domains.

#3 Using Pingdom Page Speed Testing Tool

I also tested the same web pages using Pingdom tools. I used the test server from Germany.
My hosting server was located in United States. So I wanted to check if there will be any huge difference in page loading times, when the server is far.

[wps_note size=”17″ background=”#ddc7c7″ color=”#333333″ radius=”3″]The performance grade score was C or D. It was giving a score of around 70.[/wps_note]
The pagesize was the same as GTMetrix approximately.
But the load time deferred here, taking only around 1 sec.

The following parameters were required to improve page performance.
1. Make fewer HTTP requests.
2. Compress components with gzip.
3. Use cookie-free domains.
4. Reduce DNS lookups
5. Add Expires headers.

Page Speed Test Results without using WP-Rocket

I have tested the same results after disabling the WP-Review plugin.  All the other plugins remained same.  I also cleared the Cloudflare cache, SG Optimizer cache and browser (Google Chrome) cache.

The mobile score was between 45 to 50.  The desktop score was 85 to 90.

[wps_note size=”17″ background=”#fae588″ color=”#333333″ radius=”3″]Note: One thing I observed is that the score changes, if you do the test repetitively. Also, there is some lag time before running the same test again. It is better you clear the browser cache after each iteration.[/wps_note]

Since WP-Rocket itself emphasizes not to rely much on score than on page loading time, it is not required to seriously consider the score value.

I’m giving the speed details of mobile pages (basically AMP pages on my front) for all the 3 pages tested.

Test Results without WP-Rocket using GTMetrix Tool

Test Results without WP-Rocket using Pingdom Tool


From the above test results, support team answer and reviews from other sites, we can consider that WP-Rocket alone is not the solution for all problems of slow loading websites. Well, if you are using a cheap and discounted host, you might find WP-Rocket useful in improving page load times.

But on a fast and quick host service like SiteGround and with their SG Optimizer plugin enabled, there is not much difference of page speed time. From my experience of using WordPress and other CDNs (Content Delivery Network), I have felt Cloudflare Free version with a few basic changes gives less ping time.

If you really want to have a fast mobile site, then you either should resort to a custom WordPress developer who could make changes to your site or use AMP plugins cache system. Both will require to incur some extra expenditure to make your site mobile-page-speed friendly and improve loading times.

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