We seem to have answered the initial question, and this is already marked as solved so yes it is probably worth starting another thread about the hangs and slowness. Just post back here to say when you have done so. Anyone interested will be able to follow the new thread.

Did you install Firefox portable ESR by the way. It should at least prove interesting in comparing behaviour of a previous Firefox version on your system. In fact you could just install the standard Mozilla build as an additional browser the portable suggestion is only made as it is easier than trying to explain how to install a second version of Firefox with its own profile and if necessary use of the -no-remote argument

• http://kb.mozillazine.org/Testing_pre-release_versions#Installing_multiple_versions

I will install Firefox portable ESR as you suggested (not heard of it).

You have already opened a similar thread for me, so not sure I need to open another.

Oh I hadn't yet marked this as solved, was about to do so?

With regards McAfee Site Advisor....when I am carrying out a search, I like that I can see a green or warning amber or red symbol before I click on a site. It does seem to exacerbate the problem I have though, which is why I currently have it disabled.

Thank you very much for the links and useful information. I really liked Process Explorer.

Been using Firefox ESR 24.0 for the last few days.

I have McAfee Site Advisor and Shockwave Flash enabled.

The problem has gone. No locking or sudden loss of memory usage...haven't had to shut Firefox down.

Such a relief.

But what do I do in future please? I assume Firefox ESR upgrades too?

Yes ERS does upgrade. But not in the same pattern as does the ordinary release.

The updates each six weeks do not always change the version and only include important changes normally security fixes.

• see http://www.mozilla.org/en-US/firefox/organizations/faq

So ESR will jump to Firefox 31 next but not until June. With luck some or all of these problems will be fixed by then

In the other bug Alice found (Bug 973819 - Firefox 27 high CPU usage )

2 things:
1. http://www.theydrawandcook.com/ is loading slowly - 1-2 minutes
2. After the page loads completely, on FF 26, 27.0.1, 28 the CPU is ~40% if staying on the top of the page, and <5% if scrolling to the bottom of the page.

What have you got on the computer now.

• Is the ESR an ordinary Mozilla build or did you install the ESR portable ?
• Do you still have the Fx28 Release or did you uninstall that ?

You could try the link mentioned above using Fx28 and see if you notice the sort of bad behaviour mentioned, if so there is a good possibility you have the same problem.

Thank you very much for your on-going help John.

With Firefox 28.0, which I still have....

That page loaded straight away, but:

CPU 47% top 1% bottom

So yes, that was a positive test result!

ESR 24.0 Portable is what I have.

If it is a known bug with a bug report filed we can hope it will get fixed.

The firefox side of that appears to be something to do with the JIT javascript compiler. It is possible to disable that. The result can be even worse but sometimes if there is a crash or fault condition it will improve matters.

It is a change that can be made and reversed fairly easily and could be worth a try. It certainly could not be a cure but it may be a workaround that sometimes helps. If you have mastered creating and using new profiles you may wish to test the change in a new profile.

• See http://kb.mozillazine.org/Firefox_crashes#JIT_compiler

Disable the JIT compiler by setting the preferences javascript.options.baselinejit.* to false in about:config. To use about:config navigate to it by entering in the addressbar, and accepting the warning. You then search for the prefs by entering the name or the first part of it in the search bar. Right clicking gives options to toggle the values etc.

• see http://kb.mozillazine.org/About:config

javascript.options.baselinejit.chrome

Or

javascript.options.baselinejit.content

Or both

?

When I click on Toggle the whole lot change to False?

I think I'll just stick with ESR 24.0 for now.

I've just lost all my passwords, my mail notifier and dictionary!

I don't remember all of them.

Tools > Options > Security: Passwords: "Saved Passwords" > "Show Passwords"

Empty!

This is with my previous profile, not the one I just created.

I haven't got time at the moment to deal with this.

The current version of 24 ESR is actually 24.4.0 as it was released in line with Firefox 28.0 release.

http://www.mozilla.org/en-US/firefox/organizations/all/

Sorry to hear that. I am guessing that it is the profile that has been lost track of, rather than each individual file disappearing.

As a first step back up all the profiles that you have and put the backups somewhere safe outside of any Firefox program or Profile path.

• Back up and restore information in Firefox profiles

It is best to avoid trying to restore bookmarks until the profiles have been backed up as you may otherwise overwrite and lose important versions of bookmark lists.

Next open firefox and try each profile in turn. Use the option in the troubleshooting information page to open the profile. That is the easiest method of working out which profile is being used and where it is located. Write down or otherwise copy the location including the full file name.

• Use the Troubleshooting Information page to help fix Firefox issues
• Profiles - Where Firefox stores your bookmarks, passwords and other user data_how-do-i-find-my-profile

Hopefully you have not been renaming profiles, as by default using the built in profile manager that changes the profile display name but not the profile folder name and so can create a confusing mismatch.

The profile control is achieved by modifying listings of the locations in a file profiles.ini it is not too straight forward to edit manually, ordinarily profilemanager handles that. Normally there is just the one profiles.ini file and it is in the Firefox folder that contains the Profile. With custom installs it is possible you created more than one profiles.ini.

• http://kb.mozillazine.org/Profiles.ini_file

It would be worth searching the computer for any files named profiles.ini to check whether you have multiple files. Also search for places.sqlite that is the data base that has History and Bookmarks. There will be such a file in each profile and backup profile. The search will help confirm you have located all of your profiles.

I do not remember is it firefox Portable ESR that you installed ? Or is it a standard Mozilla Firefox ESR ?

james - Thank you for pointing that out. I do actually have 24.4.0, I just looked again, I previously missed that .4.

Portable addition john. I either used your link or alice's one, not totally sure which. This I think:

http://portableapps.com/apps/internet/firefox-portable-esr

Stayed up late last night working through all my passwords again! Oh what a nightmare that is....repeated attempts. Got the most important saved again now.

No, I have not renamed any of my profiles.

about:config.....Why would everything change to false when I click on a preference (are they all called that) then toggle? How do I change individual preferences in future? Mind you after what's just happened maybe I best not!

Will study that information you just gave me now.....thanks a lot.

To try with JIT disabled change both of those pref to false and also any plain javascript.options.baselinejit

javascript.options.baselinejit.chrome
Or
javascript.options.baselinejit.content
Or both
? 

Make a note of what you change then you know what to change back.

Sorry I forgot to mention the * is common shorthand indicating any value. Some computer or web searches actually use the * as a search term. The about:config filter/search does that and also does not need the search term completing to search, but the commencement needs to be correct. You could have filtered for "javascript.*.b" That would find all the prefs we are interested in, but potentially others as well.

You are right to be wary. You should not change the prefs unnecessarily it can break things. There is a possibility of easily resetting everything to defaults as a fix, if it becomes necessary, but that may change customisations etc. Note user changed prefs display in bold. That includes prefs changed problematically. (So do not reset everything that is bold)

The modify/reset etc. options are on right clicking not left clicking. There are three types of pref integer, string & boolean. The type indicates the data type used. Boolean prefs are true or false. Integer prefs have a number value and string prefs have some sort of text.

Some of the plugins are missed in XP. So you are experiencing lock ups. Since firefox consumes more amount of CPU usage than expected, we may experience hangs. The developers are working with this issue.

I have been experiencing this exact same issue starting a few months ago. I have all plug-ins disabled, yet when I open a new tab, the plug-in container launches, along with high memory usage, causing my computer to hang. It stopped for a few weeks but has started again. I also use XP, btw. This behavior makes no sense to me given all the plug-ins are disabled (It used to happen only when Flash was enabled) This is quite a hassle to deal with. Every time I open a tab, I have to kill the plug-in container in task manager just so the computer doesn't hang.