About GT Metrix, Pagespeed Insights and Other Website Speed Testers

Make sure to read the related articles (bottom of this page) in order to learn more about specific issues you may encounter. There are endless situations one can encounter while checking the speed of a website on a website speed tester, especially considering that there are many of those. Let’s start by stating that not […]

Written By Matthew Martin

December 29, 2020

Make sure to read the related articles (bottom of this page) in order to learn more about specific issues you may encounter.

There are endless situations one can encounter while checking the speed of a website on a website speed tester, especially considering that there are many of those. Let’s start by stating that not all of them measure the same things, so it is normal to get different results depending on where you test your site. So, first of all, please read at this article by Kinsta to know how to properly run a website speed testHow to Properly Run a Website Speed Test

Our key takeaways from what we have learned in years of experience are:

  • Each speed tester measures your sites in a different way and using different algorithms, so like we said, it is normal to get different results. For example, GTmetrix is more technical, while PageSpeed Insights focuses more on user experience.
  • Each result is always different than the previous one because such tests depend on many things: the current traffic from the test server to your site, the time of the day, the load of the test server, your caching solution, etc.
  • Real browsers provide a better indication of your website’s performance.
  • The scores are a way to tell you how good a website is performing in general. If there wasn’t a score, it would be too difficult for the average user to understand the results. Such scores are a combination of many factors, most of them unrelated to ShortPixel. Since these factors change with each test, it is possible that they affect the overall score.
  • The loading time, in general, is better with our plugins and hosting. This is what Spade design is aiming for, a better image optimization and thus less page size and less loading time. Like we said, looking at the general score can be misleading.
  • Website speed testers are run by algorithms, and they are useful, but not perfect. As with every software, they also have bugs, and sometimes they give results which are not correct. Don’t take their reports as the absolute truth.


It is important to know that before doing a website speed test, you should flush your cache. Please do it in this order:

  1. Image Optimization: be sure to clear the cache for the image optimization plugin, if you are using one (managed sites by Spade Design will have this and we will do this for you).
  2. Cache plugins: Now clear each plugin’s cache (WP Rocket, LiteSpeed Cache, SG Optimizer, Autoptimize…)
  3. Server cache: Clear the cache at your host (SiteGround, BlueHost, Godaddy, Kinsta…)
  4. CDN cache: Now clear the CDN Cache (Cloudflare, StackPath…). Please do it from your CDN’s dashboardnot through your cache plugin or hosting dashboard.

After flushing your cache, you should check your site with a page speed tester multiple times in order to let all the caches work properly and rule out any false positives. I’d also check again in about 4 hours and run a few more tests.


If GTMetrix, GPSI or any other web tool complained about one or more images on your website not being optimized after you ran our tool here are some common reasons why this is happening:

  1. The image was optimized but it is not properly sized for its placeholder.
    For example for a 100x100px placeholder a 400x400px image is used. It makes no sense to attempt to optimize the image more, you just need to resize it.
    As possible solutions, you can resize the image in your WordPress and use the appropriately sized thumbnail. Or you can try our Adaptive Images plugin, it was specifically designed for such cases. (All websites managed by Spade Design use an Adaptive image CDN, unless it is an artist or photography website or we’ve been asked not to because of a special situation e.g. exact color profiles are required, or print quality downloads are need, etc.)
  2. The image was optimized but it still retains its EXIF data
    Some speed testing websites will complain about an image not being optimized enough but they usually remove the EXIF data (which can take up to 8% of the image size)If you choose to keep the EXIF data then you can safely ignore this message.
  3. The image was optimized and it still retains its color profile
    Speed testing websites will generally remove the color profile data from images. ShortPixel chooses to keep this data as otherwise the image’s colors may look altered on different browsers. You can safely ignore this kind of warnings as well.


I cannot stress this enough. As mentioned above, the scores are a combination of many factors, and many of them have no effect in your website speed. This is especially true in Google PageSpeed Insights (and GTmetrix, as their results are based on Google’s); you may think this tool matters the most because it’s made by Google, but the reality is that there’s very little correlation between getting a good score on this tool and having a good rank on Google. In my opinion, the Google Speed Test is one of the worst. The information it gives is either unhelpful for the average user or highly off the mark. In other words, scoring bad in PageSpeed Insights means very little. To illustrate this, check these two famous sites:

Tanner, from UpCity, gives a very good advice:

When it comes to site speed as a ranking factor, Google isn’t looking for a website with lightning-fast speed, it’s looking for one that can meet a user’s intent. As such, user experience and content should be the focus of any SEO campaign. Site speed is merely a small piece of the puzzle.


Sometimes one will be concerned regarding the TTFB (Time To First Byte); some hosting providers may claim that our image CDN is taking a few ms of loading time. Good news: you shouldn’t be concerned about the time to first byte (unless it’s extremely bad). Any image optimizer (and actually any plugin) by definition will take a few ms of time when loading. We can assure you that Spade Design’s plugins are among the most optimized ones, and you can try them out in a sandbox like this one: Sandbox

In addition, we recommend to read this article that Cloudflare wrote about this clarifying this situation: Stop worrying about Time To First Byte (TTFB)


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