The Page Speed Analyzer and WebPageTest are currently the only self-testing tools that are able to measure the performance uplift of Speed Kit. Therefore, we highly recommend to only use these two tools for self-testing. In general, the most accurate performance results will be delivered by the Speed Kit real-user monitoring.
The analyzer does a side-by-side comparison of your website with and without Speed Kit. In principle, the analyzer loads your website multiple times to contrast performance with and without Speed Kit. However, it does more than what you can do with your browser.
Performance report: It gives you various metrics and even waterfall diagrams for your page load.
Optimization hints: It provides suggestions on how to improve web performance for your website.
User-centric: It measures the Speed Index and the First Meaningful Paint.
Possible speedup: It tells you how much faster your website will be, if you activate Speed Kit.
Video comparison: It captures the page load, so that you can literally see the effect that Speed Kit has.
How It Works
Once you enter your website's URL, the analyzer starts two different Chrome browsers to load your website: One loads the version with Speed Kit and the other loads your website without Speed Kit. If Speed Kit is already active on your website, the analyzer deactivates Speed Kit for one of the two tests. If Speed Kit is not active on your website, the analyzer injects Speed Kit into your websites for one of the tests. Thus, you always get to know what Speed Kit currently does or could do for your web performance.
We did not implement the measurements ourselves, though. Instead, we use the open-source testing framework WebPageTest. You can access the WebPageTest Waterfalls by clicking “Show Details” below the video comparison and then clicking one of the links at the bottom of the overview (either “Without Speed Kit” or “With Speed Kit”, depending on the test run you are interested in).
By default, the analyzer simulates a desktop user located in Germany. However, you can change the default behavior through several parameters:
Mobile: Whether or not the website should be loaded from a mobile browser (true) or a desktop browser (false, default).
Run from US: Whether or not the website should be loaded from the United States (true) or from Germany (false, default).
Activity timeout: The time after the last network activity before a test is considered complete.
Speed Kit config: The detailed config parameters for Speed Kit to allow you performance fine-tuning (see Speed Kit API docs).