hello, can you try to replicate this behaviour when you launch firefox in safe mode once? if not, maybe an addon is interfering here...

Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems

also see and refer to

• Firefox uses too much memory or CPU resources - How to fix

It is rather clear that there is a plugin or several that are causing this. Both JavaScript and xpcom are using much more memory than they should. Is there any easy way to tell how much RAM an individual plugin is using since it would take hours and hours to check each one.

Alternatively is there any easy way to downgrade to Firefox 22 since there where absolutely 0 problems on that version and the spellchecker still worked?

if Firefox 23 has problems and Firefox 22 does not in an identical/similar situation there is some regression that needs investigating. Generally newer versions of Firefox should be as good or better than previous versions.

If however the problem is related to plugins the problem is that the issue is with none Firefox / Mozilla software.

What you should try is using Firefox in a new profile and in safe-mode with all plugins disabled. That should give you normal behaviour. Then enable plugins one at a time to discover which is causing problems. Note if you wish to check memory usage you should use about:memory rather than other methods such as Windows Task Manager.

• Firefox uses too much memory or CPU resources - How to fix_memory-troubleshooting-tools

The problem is that it takes 2 hours or more of browsing before it becomes really visible. Testing each plugin would take me days.

The problem is clearly related to one or more plugins however the problems with these plugins only exist on Firefox 23 and later.

Firefox 23 is clearly a step in a negative direction when it breaks such fundamental things as the built in spelling checker and plugins which have been working fine for years.

So once again I would like to ask: Is there any way to easily downgrade Firefox while keeping my plugins and settings? While I could live without most of my plugins, I really want to have a working spelling checker.

there will be an update to 23.0.1 tomorrow that - next to other things - also should take care of the spellchecker bug.

edit: this addon might be useful: https://addons.mozilla.org/en-us/firefox/addon/about-addons-memory/ - i've never used it myself though so i don't know how reliable its output is...

Problems with the spell checker not working can be caused by the path to the Firefox profile folder containing (accented) characters in the non-ASCII range.

If your Windows account contains accented characters in the user name then you can consider to move the two dictionary files (xx-xx.aff and xx-dic) from their dictionaries folder in the Extensions folder in the Firefox profile folder to the dictionaries folder in the Firefox program folder (you may need to create this dictionaries folder if it doesn't exist) as a temporary workaround because a Firefox 23.0.1 version will be released that includes a fix for this.

See also comment 13:

• bug 902532 - Spellchecking broken with non-ASCII characters in profile path

Please DO NOT comment in bug reports: https://bugzilla.mozilla.org/page.cgi?id=etiquette.html

Thank you for you help. I will wait for the update and see if it solves the problem.

The about:addons-memory showed nothing odd and a total memory usage for plugins at approximately 60MB.

Here is the about:memory page at the same time: http://i.imgur.com/BHXjOzb.png

While I am not completely sure what xpcom is I am completely sure that it normally shouldn't take up that much RAM.

a user here reported ghostery as a source for a memory leak - you might want to keep it disabled for a while and observe the use of resources...

Thanks, disabling Ghostery lowered the CPU usage by 90% and the amount of RAM used isn't exponentially growing any more. The amount of RAM usage is still a bit high ~450MB but it definitively isn't a problem any more. I'll try the dictionary workaround.

Edit: The dictionary workaround works fine after I disabled the dictionary in the add-ons list.

P.S

I did not see your post above when I posted this, but I will leave it as the suggestions may help others. 

Here are some suggestions for investigating your memory usage.

about:memory & memory reduction buttons

• Try using the built in about:memory, then try the buttons to reduce memory usage
  • do they help ?
  • specifically does it reduce the xpcom figure ?
  • also note it is possible to save load and dif the reports
    https://blog.mozilla.org/nnethercote/2013/04/26/recent-aboutmemory-improvements/

By the way I would guess the addon was from the days when about:memory was in early development and should no longer be needed.

xpcom is effectively part of Firefox but in your image is indicated as 67% of your explicit memory. On a recent test it was 0.04% of my explicit memory. That is several orders of magnitude lower than your results. It does not even list unless I use the verbose option.

Does xpcom memory usage start at a low figure after a Firefox restart and then climb to a high value or is it always high on startup ? (Same question for startup of Firefox with each of your plugins enabled as the only plugin )

Crashing
As this actually causes crashes please paste a couple of recent Crash IDs into your next post.

• Troubleshoot Firefox crashes (closing or quitting unexpectedly)

Testing
Note it is easy to setup Firefox with an additional profile. You may then try one profile with all or most of your addons disabled and another with only one plugin enabled or the other half of the plugins enabled. That sort of method cuts down on testing time when trying to isolate the problem rather than testing with each of 11plugins enabled in turn.

(You could have problems with attempting the following if you have limited memory).
It is even possible to run two instances of Firefox at the same time. This may be convenient if you wish to run Firefox for several hours in a particular test configuration but still need a Firefox instance available with all plugins enabled.

• use a separate profile for each
  • Profile Manager - Create, remove or switch Firefox profiles
• use -no-remote on the profile shortcut that is NOT the default browser
  • http://kb.mozillazine.org/Opening_a_new_instance_of_your_Mozilla_application_with_another_profile
  • http://kb.mozillazine.org/Using_multiple_profiles_-_Firefox

Ghostery had an update 5.0.3, and I noticed 2 changes- 1. No green icon, at top...- black square with count. 2. Icon No longer showing at bottom of page.

I don't know if memory leak is fixed, but iGoogle Search Suggestions stopped working in 23!- I'm going back to 22!

Please be aware that downgrading to insecure unsupported versions is not a good idea. You increase risks to your System and to your personal data.

• see Install an older version of Firefox

If you have a problem with iGoogle and it worked in Firefox 22 and with other current browsers then I suggest you start a new thread of your own

• use /questions/new
  1. Please follow the prompts to add troubleshooting information when you post the question
  2. You may wish to post back in this thread to confirm when you have done that

I had already posted the "No iGoogle Search Suggestions" question, with trouble shooting info.- https://support.mozilla.org/en-US/questions/967803?esab=a&s=&r=0&as=s

Somehow I got iiGoogle working on my 64-bit laptop (prematurely marked Solved), but then Not on my 32-bit desktop (UN-marked Solved)!?- Since then no more suggestions from guru's...? I use the same AV on both???

OK I answered in the other thread /questions/967803#answer-469293

I've had a memory leak issue since upgrading to 23.0.1

After troubleshooting the problem, I've come to realize that the leak was caused by the Skype click to call add-on.

I also have Ghostery installed (which I've seen to have been the culprit for past leaks), but disabling the Skype add-on did it for me.