Is Google Page Speed Insights an accurate tool for testing your website speed?

Turbo Web
3 min readSep 16, 2018


How good is Google Page Speed Insights?

Being the manager of a WordPress speed optimization company (TurboWeb) and having substantial experience as a freelancer in this field, I am frequently asked about how can website speed be properly tested.

The most popular testing tool out there is Google Page Speed Insights. From my experience, 9 out of 10 clients ask whether we can provide certain scores on this testing tool. Many people consider it the ultimate judge when it comes to measuring website performance. But is that really the case?

Here is the truth:

Google Page Speed Insights is just a “best practices” tool. It’s a tool designed to test whether your website has implemented all good practices when it comes to speed optimization. It doesn’t even do that too well. To better understand whether best practices have been respected, Google Page Speed Insights must be used in tandem with GtMetrix and Pingdom. Only by testing your website with all these three best practice tools you’ll find out whether every little thing has been properly implemented or not.

Also, scores on such tools are severely influenced by having 3rd party resources or other things that trigger their “good practices” alarm bells. That’s why even websites that have invested millions into their technical development, like Amazon, Facebook or Microsoft, get low grades on this Google Page Speed Insights test.

On top of this, none of these programs measures real speed for real users. Real speed can only be measured with WebPageTest — a tool also developed by Google, but known mainly just by professionals from the field of website speed optimization. This tool will test how your website behaves in real life, for real users. It will also show how every one of your website scripts behaves. It’s the ultimate tool when it comes to website speed optimization.

Unfortunately, because it requires some skill to use, it never got as popular as Google Page Speed Insights. Amateurs want things to be simple. Beginners want a tool where you can type your URL and get a grade. They then want this grade to be as accurate as possible. Unfortunately, things are not that simple.

How do PRO’s judge a website?

The most important number when it comes to speed optimization is your “Speed index” from WebPageTest. It’s the best estimate for how fast the “above the fold” area (upper part) of the page loads. For example, a web page might get fully loaded in 3 seconds, but deliver the above the fold area in just 1 second. Through doing this, the visitor never gets to stare at a white screen.

This is why all test tools penalize a website for problems that affect the loading of this upper part of the page. Like, for example, having render blocking resources or not lazy loading images.

When do I know my Wordpress website has reached the limit?

At Turbo Web, all websites optimized by us end up standing between these numbers in terms of speed index:

0.5s — 1.0s — Simple presentation website

0.5s — 1.3s — Newspaper or magazine type of website

0.8s — 1.5s — Gruesome Woocomerce shop with many plug-ins and functionality

These are the limits that can be reached with a Wordpress website after a professional, full-option speed optimization.

WebPageTest is the only test that actually measures real speed for real users. If you’ll test you’re website as a real human and count the seconds, results will be identical.


Good practice tools such as Google Page Speed Insights are good and necessary when performing a website speed optimization. A properly optimized website should generally have good scores on all good practice testing tools. BUT, one should only judge his real performance using WebPageTest.

Page speed should be a priority for your business. Statistics show that every extra second costs you 11% traffic, 7% conversions and 16% customer satisfaction. Therefore, you should treat this issue seriously and learn how to properly test your real page speed using WebPageTest instead of chasing big grades on best practices tools. Only then you will stop losing big money in the long run.

If you ever want this issue solved in a professional manner, you can always outsource it to a specialized WordPress speed optimization service like Turbo Web.