Google’s PageSpeed Insights Tool is a website analyzer which measures site speed for the total time required to deliver the content of a web page, then generates suggestions to make that page load even faster. It also displays a snapshot of Google‘s Big Query Data for a historic display of your site’s performance metrics. As speed is a confirmed ranking factor in Google Searches as of July 2018, the PSI’s website speed optimization techniques are geared toward evaluating each page via PSI as well as various independent website testing tools, then performing optimizations in order to render each page as quickly as possible and allow you to interact with them as fast as they appear on your device screen.
The median value for each metric (FCP or DCL) is compared to all the pages monitored by the CrUX report. Each metric is assigned a category, depending on where it falls in the distribution:
Fast: The median value of the metric is in the fastest third of all page loads.
Slow: The median value of the metric is in the lowest third of all page loads.
Average: The median value of the metric is in the middle third of all page loads.
An overall Speed score is calculated by looking at the categories for each metric:
Fast: If every metric of a page is Fast.
Slow: If any metric of a page is Slow.
Average: All other cases.
While Google deprecated its own PageSpeed Insights Service was officially deprecated on August 03, 2015, they provided the source code for server modules which perform the tasks listed in the output report recommendations. While many developers were less than pleased with the direct outcome of Apache and Nginx implementations, there were several third-party developers who went on to further develop on these core concepts and even create their own solutions which began with the core concepts and expanded their offerings to provide a full range of the latest in cutting-edge website performance optimization techniques, such as the Google PageSpeed Plugin known as the Pegasaas Accelerator.
While there remains a widespread group of detractors of the Google PageSpeed Insights Tool and even the notion of PageSpeed Insights vs Page Speed vs Site Speed, those willing to put in the time to run their own independent benchmarks via the most notable free speed test tools which test website speed scores, such as the GTmetrix and Pingdom speed test tools, have demonstrated that these techniques deliver the fastest experiences across the widest range of devices on even the slowest of networks.