• Firefox offers better privacy and security than Chrome, with upcoming support for 200 new add-ons. • While Chrome dominates, Firefox gains ground with user-friendly browsing experience and open-source model. • Mozilla’s focus on user privacy and transparency challenges Google’s ad-centric approach, making Firefox a viable alternative.
The way Mozilla worked and Firefox still works is there is a cross platform front-end implemented in XUL which is XHTML, CSS and Javascript. The engine underneath is the same (Gecko) but the frontend app over the top is what the user sees and controls buttons, menus, functionality.
Firefox was basically a fork of Mozilla stripped of the not-browser stuff and a cleaned up UI. It proved popular as a prototype so it grew into its own thing and Mozilla suite was abandoned. There is still a Seamonkey project that keeps Mozilla suite alive but it’s outside of the Mozilla foundation.
The reason it’s faster is that Mozilla was an entire suite expressed as a lot of XUL so it impacted loading times. XUL also had this neat trick that you could overlay XUL over the top of other XUL so the mail app was injecting buttons, menus and whatnot into the browser and vice versa. This was cached but it still had to be loaded. In addition and probably just as impactful, was that Mozilla shipped as dynamic libraries (DLLs) and a relatively small EXE, so it took time to start. In Firefox, the number of DLLs was reduced with static linking so it was more efficient to load.
If I remember correctly, XUL/XBL is dead. They removed that code a while back after they transitioned to WebExtensions. The current frontend is HTML, CSS and JavaScript.
There are still bits of XUL around but I believe the preference is to use HTML elements wherever possible and they’ve been stripping XUL elements out.