On August 8, 2017, the Rigor Optimization product released a major platform upgrade to significantly improve the accuracy and usability of its gathered performance metrics. This article summarizes those updates in more detail.
Real Browser Results
Previously, Rigor Optimization used a headless browser called PhantomJS to gather initial page metrics including downloaded content and file sizes. While PhantomJS provided useful information, our customers wanted results closer to what real world visitors to their site would use. As such, Rigor Optimization has migrated to use actual real web browser results (Mozilla Firefox engine) for its initial page metric gathering. In fact, this is the same engine utilized by Rigor Monitoring Real Browser Checks, ensuring consistent and accurate results across all Rigor products.
Prior to the update, all original file sizes reported in Rigor Optimization were based on the "size on disk" of the original files being served by the webserver. As more and more web servers have recently been pre-configured to turn on gzip compression by default, we've found the original size metric has become misleading to our users since its no longer a fully accurate representation of what visitors of your website will see.
Note that we have not altered any of your historical performance snapshot results, so your snapshot history graphs will likely see a significant change in metric reporting with this update (sizes and scores especially). While we always endeavor to keep your results as consistent as possible, we felt in this case that accuracy of results was more important than preservation of consistency.
Transfer Size example:
Advanced Multi-Page Scripting Engine Using Selenium
With this update, we've also migrated away from the lesser known CasperJS scripting framework, which has been deprecated by its creators, to the industry leading Selenium scripting framework (Selenium IDE support in this initial launch). In fact, Rigor Optimization now uses the exact same scripting interface and execution engine utilized by Rigor Monitoring Real Browser Checks. For more information, please refer to the Rigor Scripting Guide and How to use the Selenium IDE Recorder.
Using the custom script scan type allows you to easily script multi-page flows for testing scenarios like checkout carts or content walled off behind login pages.
More Timing Metrics (Start Render, SpeedIndex, and More)
Because Rigor Optimization is now using the Rigor Monitoring Real Browser Check engine under the covers, we can now expose additional performance metrics in your results. Specifically, Time to First Byte, Start Render Time, DOM Load Time, Visually Complete Time and SpeedIndex have all been added to the Rigor Optimization snapshot results, in addition to the OnLoad time metric that was always exposed. These metrics have also been added to the Get Snapshots Detail API call as well.
Download full HARs with Content
While admittedly there's a lot of change in the Rigor Optimization results from historical trends with the above updates, we feel strongly the benefits of increased accuracy and relevancy outweigh the value of preserving historical trends. With that said, we do not take change like this lightly, and will always strive to minimize platform changes to ensure consistency of your results over time.