Mozilla Firefox is still the second most popular web browser in the world, trailing Microsoft’s Internet Explorer by a still-hefty margin. But Firefox might lose its number two spot in the battle of the browsers to Google Chrome by year end.

What can Mozilla do to keep that from happening? One possible answer: a faster release cycle.

If you just recently upgraded to Firefox 4, you won’t have to wait long for Firefox 5. It’s already here, in fact, and ready for download.

Sporting new features like CSS animations, do-not-track functionality and numerous performance improvements, the latest version of Firefox may not represent as significant an update as Firefox 4, but it’s being given the version number 5 because, well, Mozilla can give it a new version number.

Brilliant marketing strategy? Perhaps. Or perhaps not.

On one hand, going from Firefox 4 to 5 in a short period of time may create the impression that Firefox is innovating at a faster and faster pace, even if the overall release cycle itself has changed less than the way releases are numbered. After all, as CNET News.com’s Stephen Shankland notes, Google releases new versions of Chrome every six weeks, and Google is winning plenty of Chrome converts, not just from IE, but from Firefox as well.

But is the impression that Google innovates faster with Chrome really the reason Chrome is doing so well? Probably not. Arguably, Google’s Chrome advertising, which may represent one of Google’s largest marketing pushes ever, is probably playing a bigger role. So releasing Firefox 6 and 7 before 2012 arrives may not be as powerful a marketing tool for Firefox.

What really matters: how the browser functions. Is performance improving? Are pages rendered accurately? Is the UI evolving appropriately? Are add-ons breaking with each new version?

From this perspective, Firefox may want to remember that you can fool some of the people some of the time, but not all of the people all the time. In the increasingly competitive browser market, Firefox will need to ensure that each new release delivers more than just a new version number.