Hands on: A look at Firefox's memory issues

Computerworld - Editor's Note: Online editorial director Scot Finnie has been using Firefox 1.5 since its release and has written about it extensively in Scot's Newsletter. This is a follow-up to earlier dispatches on the open-source browser.

Firefox continues to be the application that's the single largest memory and virtual memory hog on all my PCs. Despite that shortcoming, I haven't experienced any of the side effects detailed in my earlier articles starting when Firefox 1.5 was first released. Well, there's one I've continued to see: Firefox takes absolutely forever to launch when initiated from hyperlinks in third-party apps such as e-mail and instant messaging clients. That problem predates Firefox 1.5 though (as did the high memory usage).

But while Firefox 1.5 has been pretty clear sailing for me, not a day goes by when I don't get at least one e-mail from a frustrated Firefox user who has some mix of the problems I've described in the past, including exceptionally high use of physical and virtual memory, CPU usage that climbs to 100%, program hesitations and freezes, a launch failure that requires an operating system reboot or termination of the firefox.exe process in Task Manager, specific Web pages that don't load, and crashes.

I'm not getting as many messages as I once did, but they're still trickling in. One reader wrote:

"Not long ago you mentioned a memory hole problem in Firefox. I experience the problem on a daily basis and it's been driving me nuts. I can see RAM usage via Task Manager going up and up and up until even virtual memory gets swamped. As soon as Firefox 1.5 came out, the memory problems began. If I use IE6 instead of Firefox, I have no memory problems. I've searched the help forums MozillaZine.org without luck. Does Mozilla think it's fixed this problem?"

What he is describing is a memory leak, and it sounds more serious on his machine than on some others. I don't see an ever-escalating use of memory, but some other people have. Because a small number of people are struggling with this, I'm going to pass along a tip that has worked for some users, although I'm quite sure it won't work for everyone.

Start by checking how much memory Firefox is using. There are many ways to do this, but under Windows there's only one easy way that everyone has access to. Press Ctrl-Alt-Del once. In Windows XP, that opens the Task Manager. Click the Processes tab, and check the numbers on the firefox.exe line under the headings "Mem Usage" and "VM Size." Click the Mem Usage header twice to sort the rows by memory usage, highest to lowest. Is Firefox at the top? Is it a six-digit number? If so, Firefox is consuming a lot more memory than it should. Watch these numbers over time as you run Firefox to see whether they grow significantly.