Firefox 3.0 has been a long-awaited update to Firefox 2.0. has touted many of the improvements in Firefox 3.0 in the areas of speed, standards compatibility, and browser features in general. One of the biggest areas Firefox 3.0 was supposed to address was memory usage.

Firefox is a great Web browser, and I use it daily. One of the major irritations, however, is the fact that it likes to gobble up memory as you browse around the Internet with it. As you open and close sites, whether in separate windows or separate tabs, Firefox scoffs up more memory and very rarely releases most, if any, of the memory back to the OS when you close things. Eventually, the whole system slows down, and you have to close Firefox or, worse, kill the process to get the memory back. When memory usage grows too big, Firefox 2.0 invariably locks up or crashes. I’ve noticed this running Firefox in OS/2, Windows, and Linux, so it’s not an isolated problem to one operating system.

Firefox 3.0 to the rescue?

With any new release of software, you can almost guarantee that the new version is going to use more resources and be more of a pig. claimed that Firefox 3.0 was going to be different. So, when Download Day hit, I wanted to make sure to grab the final release of Firefox 3.0 as soon as possible. I then decided to see if the memory usage had improved any.

Sadly it did not. If anything, it got worse.  I conducted a semiscientific test on my production machine. This is a 2.8 Ghz P4 with 2GB of RAM running Windows XP SP3. I first ran my install of Firefox 2.0 and measured the memory usage of Firefox when visiting TechRepublic’s Web site. I went to the home page, loaded all the tabs across the TR front page, measured usage, and then closed them. After that, I installed Firefox 3.0 and did the exact same thing all over again.

I compiled all my results in a Firefox 3.0 Memory Usage Photo Gallery. I was pretty disappointed. Not only did Firefox 3.0 start off using more memory than Firefox 2.0, it also failed to release all the memory back. In fact, it held on to 1Mb more memory than Firefox 2.0 did.

I tried the experiment a couple of times on the same machine. The memory usage varied each time, but the results were about the same every time. Firefox 3.0 took more memory and released less when it was done than Firefox 2.0. The next step is to install Firefox 3.0 on other machines to see if it’s a trend or just some type of fluke.

(Update 6/19/2008 4:00 pm:  I reran the tests on another machine running openSUSE 10.3. The results were essentially the same. Firefox 3.0 took more memory than Firefox 2.0 and refused to give up the memory when I closed the TR tabs. Check the Photo Gallery for the new screen shots.)

The bottom line for IT Leaders

Although anecdotal evidence of a problem isn’t the same thing as rock-solid proof, it can be strongly influential. Firefox 3.0’s seeming memory problems show even more that you can’t always trust the claims of a software vendor when they’re telling you how great the next release of a product is going to be. Having a testing environment in place is imperative. Check the claims and make sure everything works the way it’s supposed to before you blindly roll out a new product.