Hi,
We show the exact same versions to the test sites & to visitors. What you wrote is not true for us. Here what we do,
When JavaScript optimization is on, RabbitLoader utilizes the multithreading feature of the web browser to fetch the resources. This helps to keep the main thread of the browser free as the tasks are offloaded to the worker thread. Keeping the main thread free makes the browser receptive to the user’s interaction quickly thereby improving Total Blocking Time(TBT) and Time To Interactive(TTI) matrices. However, the resources pulled by the worker thread may not appear on reports of the PageSpeed Lighthouse test or GTmetrix. The only known way to verify this is by loading the page on the local browser and tracking all fired requests on the ‘network’ tab.`
Thank you.