One possibility is a malware problem.

Memory usage depends a lot on firefox & site usage, if you have hundreds of open tabs many with video and animations or large databases, you use more memory than having a couple of plain text pages open. A lot of the memory will of course relate to firefox extensions rather than the core software.

Can you give some indication of what you are doing whilst the memory usage rises?

If you navigate to about:memory by typing that into the address bar the resulting info may help you track down where the memory is going. Compare the results with what happens when

1. you initially open Firefox, using only a blank page as the home page
2. after the Firefox has been left unused on that initial blank page
3. with your standard home pages on initial startup
4. after a few hours usage

Part of the reason for a slow shutdown could be because you have a lot of plugins, and clear History/Cookies on closedown. There is a known bug in firefox that opens multiple instances of plugincontainer.exe when cookies are cleared, IIRC it is fixed in some newer versions but not yet in Firefox 10. (This particular bug is not resolved by disabling plugins) If Firefox is clearing History on closedown adjust the setting so that for a tial period this does not occur.

• see Delete browsing, search and download history on Firefox_how-do-i-make-firefox-clear-my-history-automatically

Try using Firefox in safe mode

• do not make changes when the first dialogue Window opens, just click on continue
• whilst in safe mode also disable all plugins
• repeat the suggested trials above and see if matters have improved

See also

• firefox hangs
• high memory usage
• is my firefox problem a result of malware

You or your wife should open a new thread by asking a separate question about the Mac.

John99,

Thank you for your reply; here is my response.

I never had as many as 100 tabs, and when I saw your reply I had about 30. While the memory used was rising I was generally doing nothing. In fact, I repeatedly opened FF and Task Manager and, hands off, just watched the memory use increase--slowly and with some dithering, but on average rising. It would start at 200 to 300MB and reach a GB in a day or less. I observed no difference whether plugins and extensions were enabled or disabled, or whether safe mode or normal mode was used. I had cleared cookies and cache. I only had a handful of plugins and extensions.

Yesterday I did invoke 'about:memory but I am not a programmer or computer systems guy and I had no insight re what I was looking at. Today, I cleared my history and in so doing lost all my tabs. I also ran ARO 2011 repeatedly until I was sure my Registry was clean.

Opening FF after these operations, memory started at <70MB, but it is still slow to open and does not close cleanly--the process has to be manually killed. Thunderbird--with a lot of email stored-- is also slow to open, and my sense is that my apps in the Start folder are also slow to open, even after the registry scrub. As I write this, memory use on FF is up to 80MB; the only open tabs are about: memory and this page. I will now attempt to restore some of my tabs.

With 9 tabs, memory used is about 161MB, and it looks stable at the moment. I will rebuild my tabs and respond further tomorrow.

John99,

It's been two days--my bad. Killing history (and my tabs) has slowed, but not stopped the memory creep. Now, with about a dozen tabs open, FF opens at about 124MB. It was almost triple that when I closed it a few minutes ago, before re-opening. It opens reasonably, but still closes erratically, usually leaving the process's .exe file open.

I would appreciate some detailed steps how to proceed. Again, I cannot really interpret the display in about:memory.

On my wife's Mac, I killed history and cookies, and FF appears to have stopped hanging.

Again, we never had these problems before version 10, AFAIK.

If it is reaching 1GB maybe you have a problem needing checking; otherwise it is probably ok. If you are seeing high memory usage, then about memory should give you some indication of where that memory is being used. Compare the instances where you have ca125MB with the 1GB results. About memory also has buttons that should allow you to reduce the amount of memory used.

Since this exchange began, several friends familiar with FireFox have told me that this memory leak problem is well known in the FireFox community and that it resides in the application code itself. I myself cannot recall having this problem before the current ver. 10. Is this so?

All browsers at some stage or another have problems; or reported problems with memory usage. With Firefox it has many possible software extensions, and often the roblem relates to the other softwareor the site used.

By now you should be on Firefox 11 rather than 10.

There is a project to track memory problems and improve Firefox see

• https://wiki.mozilla.org/Performance/MemShrink
  • http://blog.mozilla.com/nnethercote/category/memshrink/

Right now, I am on ver. 11.0, with 21 tabs open, and 540MB of memory is in use by FF. I will now close and restart FF.

FF restarted. Memory use 240 to 260MB.