Google PageSpeed gives you recommendations on how to improve the performance of your web site, but it does not actually measure the speed (aka loading time) of your website. If your site loads fast, you can safely ignore PageSpeed’s recommendations.
The Need for Speed
Speed, i.e the loading time of your site, is the most important metric. This is what counts for user experience and for SEO. When the Google bot crawls your site, it cannot see your “grade”, only your speed.
Did you know that Google PageSpeed does not even measure the loading time of your site?
Use Pingdom Tools to measure the load time:
Chasing a Grade is a Waste of Time
Hardly any site gets a perfect PageSpeed score, in fact, it is very, very hard to achieve. You should not take all of the suggestions from PageSpeed in a literal sense, because sometimes they are unrealistic, or even impossible.
For example, it may tell you to minify or add expiry headers to a file that is not hosted on your website. This is impossible. In the below example, only Facebook and Google themselves can add browser caching to these files:
If you use a CDN on your site, PageSpeed might give you a lower score for that, although in many cases a CDN may provide better speed for your international visitors.
Or in case it grades your site lower because you could save 1kB by compressing an image, that 1kB is just not worth bothering about!
What is PageSpeed Good for?
In some cases, PageSpeed will alert you to problems on your site that you can and should address. For example, it might alert you to the fact that your content is not being GZIPed. WP Rocket adds the rules for GZIP by default, so if PageSpeed still gives you a warning, that might be a sign your server does not have GZIP activated.
(Learn more: Enable GZIP Compression)
Or PageSpeed might alert you that you have a lot of large image files that could and should be compressed. This is a good recommendation which you can actually act upon.
(For further information read our blog post Image Optimization—An Easy Win for a Faster Site, and have a look at our new image optimization and compression plugin Imagify.)
Here is a great example of an opportunity to improve, because you can save 750kB—an 87% reduction in size. This would have a good effect on your loading time:
Guidelines for Using PageSpeed
Use PageSpeed as a tool that might provide some pointers, but your goal should always be to improve your actual speed, not your Page“Speed” score. Remember: PageSpeed does not even measure your site’s speed, even though it says “speed” right there in its name.
Always read PageSpeed’s recommendations carefully and implement those that are possible to implement for you and worth your time. If PageSpeed demands you should do something impossible (like minifying external scripts you have no control over), by all means, ignore that!
Always focus on speed, and don’t waste time chasing a virtual score. Use an actual speed testing tool like Pingdom to see the impact of any changes you have made on your site.
Forward from https://wp-rocket.me/blog/correctly-measure-websites-page-load-time/