The Pale Moon project is the work of a single individual (Mr. M.C. Straver), using contributed Open Source code to create a full-featured, speed optimized browser based on the popular Firefox browser. Having seen the advantages on other systems (e.g. Linux) with regards to programs being compiled specifically for the capabilities of the machine it is installed on, it became obviously clear that Windows users were at a disadvantage: Mozilla only releases Windows executables with maximum compatibility in mind, meaning that Firefox is made to run on as many different systems as possible, sacrificing efficiency and speed in the process to be compatible with, by current standards, absolutely ancient hardware (backwards compatible to the first Pentium processors from 1993).
In addition, later versions of Pale Moon aim to provide more freedom of choice than Mozilla about how people want to browse the web, which tools or extensions they wish to use, and which feedback users want to see; efficiency, after all, should not stop at the engine of a browser, but extend to all parts of it, including the user interface. Specifically, Firefox 4 and later have redesigned the user interface after the visions of the Mozilla Firefox product directors and user experience team to provide a minimalist interface; unfortunately also removing essential functions and making a few less logical design choices, confusing minimalism with cleanliness.
Users will find a slightly more conservative approach to changes in the user interface in the Pale Moon browser, which, although very close to Firefox, is (now more obviously so than before) a different product. However, these differences in layout do not prevent anyone from configuring their browser interface to exactly the way they want it to look and work (including like Mozilla Firefox's default layout if they so wish).
Pale Moon is a middle road, cutting away support for ancient systems to achieve a significant speed and efficiency increase, but not trying to squeeze the last few percent more out of it by limiting the range of systems it will run on even more. It aims to not waste computer resources and power on inefficient programs, while at the same time serving a wide range of systems that are currently in use around the world. As one person remarked when the first version of Pale Moon was just released: optimizing for only the very latest systems and limiting Pale Moon to run only on those would be rather pointless, as those systems have enough horse power in excess to not make the few percent extra even noticed that would be gained by additionally using their specific hardware capabilities.
Pale Moon will be released independent of Mozilla Firefox, as it will take time to build and test based on release code, and add Pale Moon specific enhancements; the Mozilla release schedule is not followed. Pale Moon is an independently developed product based on Firefox, but will not follow Firefox to the letter. This is still a project run in free time and without commercial incentives, and testing the browser on at least a few systems before releasing it to the public is an important step in releasing a browser that is stable enough for public, daily use. Because Firefox shares its source code over several different platforms, patches that are implemented for a new version quite regularly do not apply to Windows browser builds and are therefore irrelevant to Pale Moon development. Pale Moon will be updated only for select and relevant updates of the Firefox base source code and otherwise develop independently on the chosen version of the Gecko engine.
This also means that Pale Moon will not be built based on beta, release candidate, milestone, or other development releases of the Firefox source code (there will not be any Pale Moon "nightly", "aurora" or "beta" builds available to the public). Only relevant "Release" source code will be used to ensure stability.