Mozilla has enabled a new feature in Firefox Nightly on Windows 10 called skeleton UI, the idea is that when you start the browser on the first boot, the browser shows a spartan window just to show that the browser is loading. According to Doug Thayer, a Firefox Platform Engineer, the change will give users a visual indication of the browser loading as much as 15 seconds faster than normal.
Typically, Firefox should load fairly quickly on subsequent launches but when launching it for the first time after boot it can be slow as data on the hard drive has to be accessed. By offering a skeleton UI, users will know that Firefox is loading and not try to mash the Firefox icon which will only cause delays as several more browser windows attempt to open.
The skeleton UI will show the outline of the URL bar and the tabs but icons in the browser chrome, tab names, and strings in the URL bar are just represented by thick grey lines to show that those bits of information are still loading.
As with other features Mozilla attempts to implement in Firefox, the skeleton UI is currently only available on Windows 10 systems. It’ll likely come to other supported Windows versions soon enough but there’s also macOS and Linux which would benefit from the feature too. Once the skeleton UI launches on the stable branch on Windows 10, hopefully, we won’t have to wait long for it to show up on other platforms.