It has been a while since Mozilla showed big progress, although Firefox 3.5 and 3.6 showed important improvements in the areas of JavaScript performance and separate plugin processes. But that was all just a game of catching up with Chrome, Opera and Safari.

For the most part you'll probably think that Firefox 4.0 is another sequel on catching up with the competition, and well, that cannot be denied. Regardless of who was first or last, this beta is only a rough example of what to expect sometime this year when the final product is finished.

The first thing you'll notice is the focus on platform integration. Previous releases just don't fit in well on Windows, and thus 4.0 finally leverages Aero found in Vista and 7. A new Firefox button in the top corner compresses the normal menu into a most often used mini menu, reducing vertical space used by non-browsing content. No doubt you'll find this similar to Opera's approach (which actually shares space with tabs, while Firefox does not) or the (recently combined) page/tools drop down menu buttons in Chrome. Just like the competition the tabs are now at the top on Vista and 7. For other platforms like Linux and Mac there are some small changes, but most of the work is just not finished yet (such as tabs on top).

One exciting change introduced is experimental Direct2D hardware acceleration, similar to IE9 (which is also in test phase). This may improve performance significantly if executed correctly. For Mac there is acceleration through Core Animation for plug-ins if they support it. Hopefully we'll see full hardware support for all platform in the later test releases. Of course there is more such as WebM support, separate plugin processes for all platforms (not just Windows and Linux), WebGL support, and much, much, more.

Do note that this is a rough release and certainly not polished in looks or functionality, when trying your downloaded copy. Mozilla shows that Firefox isn't at its end yet, 4.0 looks to be major leap. The question remains, will this leap be big enough against the aggressive competition like Chrome, Opera and Safari or even IE9?