A Mozilla developer revealed one of the hidden techniques used by Firefox 57, also known as Quantum, to improve page loading times.
Mozilla has already mentioned a number of architectural changes to Firefox Quantum, which seem to have yielded improvements in speed and performance.
But Firefox 57 has another secret that it uses to achieve faster page load: it delays scripts from monitoring domains, such as www.google-analytics.com.
Η technique it was developed by Mozilla engineer Honza Bambas, who calls it “Tailing”. It works by delaying tracking and tracking scripts by opening a page, offering better load times.
The feature is not intended to improve privacy, although it relies on data from the feature protectionFirefox privacy policy Tracking Protection.
Cutting or to say better, the delay of these scrips simply prevents them from loading, and does not completely disable them.
So we can say, that the best performance in loading a page is achieved with change to the priority the browser gives to the location and tracking requests of each page.
“Requests remain pending while there are other requests from the page still loading and only for about 6 seconds. The delay only applies to scripts added dynamically or as async. The tracking images (tracking technique) are always late. But it is legal according to all HTML specifications, and it is assumed that well-constructed sites will not be affected in their functionality, "says Bambas.
This technique seems to work well, although in some cases it shows a blank page for a few seconds instead of gradually loading the page. Bambas refers to the Google page, Page-Hiding Snippet which uses as an example where this can happen.
However, as he points out “his intention tailing is to help with performance by delaying something that is not supposed to be visible. "
In addition to all the above, Firefox also runs the project that will display all HTTP pages as unsafe.
Currently showing prealerts on HTTP pages that manage credentials or financial data.