Speed Kit is built on a new web technology: Service Workers. Speed Kit's Service Worker is activated when a user visits your website for the first time. Therefore, Speed Kit reaches its full potential after the first load – when the service worker is already ... well ... working.
Testing your speed with Speed Kit with tests such as Page Speed Insights / GTMetrix / Pingdom will not work properly and will not show you much improvement. The main problem here is that for your users the Service Worker will be installed at the first load and then immediately usable on the second load anywhere on your website (and all loads afterward, even when returning to your page later). The tests mentioned above only consider the “first load” of your site and are therefore not able to install and make use of our Speed Kit Service Worker.
Let's look at an example of a normal user visit: He opens your landing page. The speed of this "first load" will be the normal speed of your own server. Then the Speed Kit Service Worker gets installed, right after the page is loaded. Next, the user navigates to another page on your website ("second load"). At this point, Speed Kit is active and will accelerate that page load already. When the user exits your page and comes back, Speed Kit remains activated and will accelerate all future requests to your website.
We recommend using our open-source Page Speed Analyzer which is based on the open-source WebPageTest and also tests the second load, showing the full speedup we provide. It does a side-by-side performance comparison of the time it took to load your website with and without Speed Kit. In addition, it provides you with:
- Performance Report: The analyzer gives you various metrics and even waterfall diagrams for your page load.
- Optimization Hints: The analyzer provides suggestions on how to improve web performance for your website.
- User-Centric: The analyzer measures the Speed Index and the First Meaningful Paint (see above).
- Possible Speedup: The analyzer tells you how much faster your website will be if you activate Speed Kit.
- Video Comparison: The analyzer captures the page load so that you can literally see the effect that Speed Kit has.
If you want to test on WebPageTest yourself, remember to "include 2nd load" in the advanced options.
If you are worried about your SEO-rank, keep in mind that Google does not measure website speed in a test environment to determine your rank, but instead uses real user data. This is why your SEO will get the full benefit Speed Kit provides.
If you would like to have a look under the bonnet – everything in our Page Speed Analyzer is open-source and can be seen at our git repository.