Usage pattern
I tend to think if you leave the computer on for a fortnight at a time and open up to 666 tabs you may have an unusual usage pattern and be more likely to open websites that could contribute to memory problems.

Memory Check & Reduction tip
I do not pretend to understand the mass of data in about:memory but you may be able to notice comparing the results what it is that is actually eating up all the memory. In addition

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

• To access about:memory simply key it in to your address bar and hit return. (If you have high memory usage it could take a minute or so to produce a results graph). Note you will get additional info as you run the mouse pointer over items.
• That gives more relevant results than task manager
• about:memory has buttons that reduce memory usage
• may be worth also looking at about:compartments

Crashes
If you do have a crash please provide recent submitted crash IDs. Navigate to about:crashes the crash Ids will start with bp- please paste the last two into your next post.

• Troubleshoot Firefox crashes (closing or quitting unexpectedly)

if Firefox is running out of memory and crashing; using about:memory to reduce the memory could conceivably be a workaround that prevents the monthly crash.

: Windows 7 64-bit, running in test mode
Not sure what you are referring to here. You do not seem to be running in Firefox's safe mode

• Diagnose Firefox issues using Troubleshoot Mode
• Firefox is stuck in Troubleshoot Mode

to John99: as far as usage, i was using my examples to show how wildly varying situations seem to have no effect on the length or regularity of my error. the only webpages i had in common were Yahoo Mail and another page of equal net travel regularity, other that that i had a couple webcomics (that i hadnt changed in days, so i doubt thats the issue), TvTropes (wiki type page is not gonna be the problem for the same reason as Yahoo), and Fanfiction.net (same thing). also, the slowdowns happen regardless of what im doing or have been doing, in fact the lagspike usually happen right when im in the MIDDLE of a fanfic chapter, so its not related to what im doing or have been doing recently... i doubt the pages im on is the issue at all unless the actual leak is a part of Flash (whihc is plausible)

ignore test mode, it has to do with the os, and as stated this started long before i did that. as for crashes, i mentioned they are rare. also im pretty sure theyve all had to do with flash player being overworked and bringing firefox down with it. but ok, if you still want them here the IDs are: bp-b3632d45-37d4-4105-b37b-6dc4c2130901

bp-4df905a4-b68c-429f-ad5a-dadec2130901

tell me if i posted the wrong thing.

finally: the biggest factor in this, is that it hits SUDDENLY, its like a crash but only really slow instead of totally busted, and it fixes itself somehow if i wait. every time i am told to use "about:memory" to check whats happening, i rage because i CANT, while this goes on firefox does not respond to anything, any command i give it will simply time out and be ignored. ie it will be (Not Responding). since the memory checker is inside firefox, and by the time its fixed the issue is gone, im not going to get anything out of about:memory. its not going to fix anything either for the same reason.

(will be editing this post from now on if possible rather than making new ones.)

EDIT: forgot to add: when i say monthly that's a rough guess as i don't track time very well. its not truly regular. its just annoying because it always seems to hit when im using the computer. (which isnt hard, these days im on the computer basically 24/7 unless im asleep). also, i cant really test in safe mode. as i cannot predict when this will happen due to irregularity and i require multiple plugins to work that Safe Mode would disable in order to go about my daily net usage (flash in particular, its everywhere), i cannot effectively use safe mode. even if i did, and it didnt occur for months, id have no idea if safe mode actually fixed it or if it just didnt happen at all over that timeframe.

Please read this and post back as to whether you wish to attempt to run two instances of Firefox as a troubleshooting step. Post back again after your next monthly crash. Please post a reply rather than edit the post, otherwise no-one will notice your edit.

Crash Reports
Yes you did post the correct things but they turned out not to be too useful. Maybe the next one will be more useful.

About Memory
If for instance you run that each week, and save the results by using the option on the page it may offer some clue when you do actually get the crash or hang, as you will have a report from shortly after recovering from the last problem, and another shortly before the new crash/hang. About memory just possibly could fix something because of the reduce memory options it has. If your memory leak is building up and you are able to use the reduce memory option successfully it may solve the problem

Troubleshooting running two instances of Firefox
Yes I see your problem trying to troubleshoot in Firefox's safe mode when you need a browser working continuously and with FlashPlayer and extensions required for most of that time.

This is something I do not often suggest but with 6GB RAM you could run 2 instances of Firefox simultaneously.Keep both instances open, use one in safe mode and do as much browsing on that as possible. You could at least initially run the safe mode instance with FlashPlayer enabled.If you discover safe-mode prevents crashes we should be able to fairly easily narrow down the cause.

Crash IDs
Mainly for forum cross referencing purposes

• Reports for CrashIDs
  1. bp-b3632d45-37d4-4105-b37b-6dc4c2130901 OLD CRASH ! Fx 4 2011 ??
     • Crash Signature: UserCallWinProcCheckWow
     • Related bugs include
       812186 NEW crash in js::InvokeKernel @ UserCallWinProcCheckWow with Norton Confidential 2013
       829909 VERIFIED FIXED crash in nsWindow::Enable @ UserCallWinProcCheckWow
  2. bp-4df905a4-b68c-429f-ad5a-dadec2130901
     (Flash Related) Old Crash again, but bug still actively being investigated.
     • Crash Signature: F_1501316395__________________________
     • Bug 895427 - [adbe 3600117] Videochat crashes Flash in F_1501316395

SWAG

Take a look at your security programs, to see what schedule those programs are set to for a full scan - likely maybe monthly? A time when you would typically be using your PC?

Also, take a look at Windows Control Panel > Scheduled Tasks to see what is set there.

thanks for all the help, ill start saving backups of About:memory every so often, next time it happens, ill post the 2 most recent (ie before and after). Please note though as I have said multiple times my problem isnt a crash, its a hang. while i can force it off by using task manager to shut off firefox, if i let it sit for an hour it goes away. i cant give specifics as to how it goes away as ive never had the patience to wait that long and usually go read or watch a movie, and it works when i return. thanks for the crossref on the crashes, the first one is apparently cuz of my laziness (i should really update firefox heh), and the second was indeed a flash based crash. neither had anything to do with this problem. helps to remove that from the list.

to edmeister: thanks for the suggestion, but i already know its firefox due to watching the memory usage skyrocket during the event. also i run Avast! antivirus and havent needed an actual system scan since i installed it. damn thing catches EVERYTHING.updates are on auto, but avast pops up messages when it does that.

oh yes, not gonna try the double firefox thing, i have enough trouble as it is keeping track of tabs without that kind of thing. thanks for the suggestion though.