Core Web Vitals Test WITH and WITHOUT Optimization Plugin using GTMetrix

Webpage performance test with and without Hummingbird Pro plugin of WPMU DEV. Lighthouse page speed test. FCP score is higher in desktop.

Google has long said before that page speed is one of the important ranking signals. Load time less than 3 seconds is a good indication of a well optimized site. Each site is unique. WordPress has different resources like JS, CSS, HTML for static content.

WooCommerce kind of shopping cart will produce dynamic pages. Images and Video content will add to the already congested space. Plugins will produce their own static and on-demand files.

Also Read – Railgun and Auto-Minify in Cloudflare – Their Role in Web Page Load Speed (Case-Study)

Hummingbird Pro is one speed optimization plugin from WPMU DEV that promises better load time of pages. Cache files, GZIP compression and Asset Optimization are its main features.

In my case-study I found that it does not give a good Core Web Vitals and page optimization score.  The website speed depends on various factors like number of images, resources loaded, type of server, number of plugins used, cache mechanism.

Also Read – Using Cloudflare to Improve WebSite Speed  to less than 90 secs

To see if the site has issues or needs some more optimization, I wanted to tested with another web page speed test tool. Since, Hummingbird performance score is not completely understood. Each website loading speed test will give different test results based on the tool and origin of source.

For this purpose, I am using AMP and desktop version of the same page using GTMetrix tool. Same location and browser were used.

GTMetrix Web Page Speed Test – Performance Score with Hummingbird Pro

Following test results with desktop and mobile version.

The latest GTMetrix tool uses the Lighthouse service. This is very much close to Google PageSpeed Insights tool. LCP and CLS are shown in Search Console tool. If there are any problems, then warnings and errors are shown. LCP of <2.5s and CLS <0.25 indicates good performance metrics.

Using a page optimization plugin like Hummingbird, I expected that it would be “A” grade. Though we cannot strictly believe on web page load time for ranking results, it gives a clear indication that one plugin cannot do it all. After May 2021, the Core Web Vitals are going to be part of the signals.

FCP was in red. This indicates that the site requires more optimization. Hummingbird could not remove this error.

In this case, we can see that these metrics are almost met. But still some more improvement is needed in terms of speed index.

The mobile pages were served using AMP for WP plugin. This makes the site load blazingly fast on Android and iPhones. As can be seen above, the GTMetrix Score was “B”. This has improved over the desktop optimization score. Though there was not much difference in terms of LCP and CLS metrics. FCP improved to orange. TBT was also 0ms, compared to 179ms on desktop.

Test Scenario

I wanted to see how the same site will perform WITHOUT Hummingbird Pro. All the things were kept same. This include the speed test tool and server test location. The only difference was I uninstalled this plugin. There could be some caching issues, as the site was being served using Cloudflare CDN. But I made sure I cleared all of them, before testing without this page speed optimization plugin.

GTMetrix Test – Without Hummingbird Pro

I uninstalled the plugin including the transient options.

The desktop and AMP version of the same pages were tested using GTMetrix.

Since the site was not having any third-party ads, Core Web Vitals did not show much variation. Only LCP values were higher without using Hummingbird Pro plugin. TBT and CLS were within limits. The second screenshot was taken after second iteration.

That’s why slight variation could be seen. TTFB and Fully Loaded time were within good range values.

A similar test using the AMP version pages and GTMetrix was carried out. Without using Hummingbird Pro, there was slight change in the Core Web Vitals. The GTMetrix grade was also degraded to “C” without using the above web page speed plugin. But except for FCP, others were in orange or green.

Since mobile indexing is of priority in getting better results in search engines, it is better to use AMP and Hummingbird Pro together. Also, as per the recommendations of the speed plugin, if we can move the CSS which not required to below the fold or to footer, you may get better results.



The GTMetrix tests carried out on a minimal site with and without Hummingbird plugin. The site was by itself loading fast enough. Since we were using an AMP plugin, the speed index and LCP values were GOOD without the plugin. Since there were no movable elements, CLS also gave a PERFECT score.

These two tests indicate that a good server with CDN and fast theme, should do the job for normal WordPress websites. But if you are having large number of images and resources, then optimization plugins will come into play. To test these results, more rigorous test on a bigger site with huge number of assets is to be compared.

Until then, Hummingbird Pro doesn’t make a difference if the server is fast enough and theme is speedy.

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