To enable multiprocess you need to do the following
Search for browser.tabs.remote.autostart in about:config and set all variables to true.
No need to force it since firefox48
Also read https://support.ant.com/hc/en-us/articles/115000513446-Firefox-51-Multi-Process
THAT 'autostart' actually does not work. The story is that it does but it does not always work.
I.p., if there is any addon that is supposed to be non-compatible with multi-process it will not allow/enable multiprocess.
That's why
browser.tabs.remote.force-enable true
exists. E.g.,
AdBlocker Ultimate
The Camelizer - Price Tracker
Clear Fields
Advertising Cookie Opt-out
extensions are all listed as incompatible with MP but I have yet to see how.
Thanks for the list!
I seem to have lost mine(at least temporarily) and this fits just fine. 
[quote="BS86, post:1, topic:20468"]
RAM usage is still less than Chromium-based browsers.
[/quote]You must not have a lot of tabs open.
That means "autostart" is safe approach. Till today i thought i have multiprocess firefox running.
[quote="rahulprabhakar, post:17, topic:20468, full:true"]
That means "autostart" is safe approach.[/quote] Yes it is. It S/B on by default ...
[quote="rahulprabhakar, post:17, topic:20468, full:true"]Till today i thought i have multiprocess firefox running.[/quote]Yes I had that too back with Ffx-48-beta. It took me a while to realize they do not force multiprocess even on the -beta builds(which I think is odd). The browser.tabs.remote.force-enable true is the only way I know of to test all installed extensions for multiprocess compatibility. One also must use the Compatibility Reporter of course.
I've tested the extensions with & without MP on and, so far at least, have not found any difference with any of the extensions, whether marked as compatible or not compatible. Same issues exist either way, if there are any.
I'm not certain about the Opt Out extension yet. ...that will take some time.
Good Luck & ...
Have fun!
[quote="BS86, post:1, topic:20468"]
Telling Firefox to cache to RAM instead of disk-only:
[/quote]I used the tips. Pretty much the same as have used before, IIRC.
I still have same issue as have had with Ffx ...for years:
Press [back|foward] button to load the previous page and Firefox goes into some zone where it just sits there and has a conversation with itself:
OMG! $USER WANTS TO SEE THE PREVIOUSLY DISPLAYED PAGE. OMG! WHAT DO I DO NOW? OMG! FIND THE CACHE! OMG! I FOUND THE CACHE! OMG! IS IT IN THE CACHE? OMG! OF COURSE IT IS IN THE CACHE! OMG! LOAD THE CACHED PAGE! OMG! NOW RENDER IT! OMG! HOW DO I DO THAT? OMG! USE THE PREVIOUS RENDERING THAT IS IN THE FSCKING CACHE? OMG! YES!
...or something along that line of absolutely ridiculous conversation with itself.
THEN the page finally loads. It, on this system*, currently, takes no less than 3 seconds and normally/usually longer to go forward or backwards. I won't even discuss what it was like on the AMD dual core, dual CPUs at 2.6GHz other than to say: painful.
Itsa friggin joke. Phoenix was never like that. Chrome is not like that. Chromium is not like that. AFAIK, it is only Firefox and some friends(derivatives) that do that stupid, irritating, time-consuming nonsense.
[Sorry if it seems like a rant but trying to put extra emphasis on the issue. 
]
Do you know of any other tweaks to get Ffx to load & render properly and faster?
...
* OS: Manjaro 17.0 Gellivara; Kernel: 4.10.8-1-MANJARO x86_64;
CPU(s)~2 Quad core Intel Xeon X5687s (-HT-MCP-SMP-); Mem~2901.0/24104.9MB; NUMA~2 nodes; Network~2x Intel 82576 Gb; HDD~4961.0GB(17.9% used); GPU~GeForce GTX 1060 6GB; Resolution~3840x2160; GLX~4.5.0 NVIDIA; GP106 ~375.39; DE~KDE 5.32.0 / Plasma 5.9.4; WM~KWin; *.
I have a weird problem now - Youtube videos just refuse to play.
After recent Manjaro Update for 2017-04-02. Could mesa be the cause or hardware acceleration or multiprocessing. See attached snapshot below
try refreshing firefox profile OR create new profile to validate if this is just profile specific or generic issue
Do this
firefox --no-remote --ProfileManager %u
then create new profile.
[OT]
The Annie Lennox YT video, https://www.youtube.com/watch?v=HG7I4oniOyA&index=2&list=PL8LTysrNMvaGEUMl0LlSLoz2C1-4Mej0J, plays fine for me. I did the 04-02 update last night.
BUT I'm using Mozilla's Firefox.
$> mozilla-firefox --version Mozilla Firefox 52.0.2
Which Firefox do you use? I will assume from the KDE Plasma in your info that you use the "enhanced" version, firefox-kde. Perhaps try the other, firefox, but, NB, it will replace the 'enhanced' firefox-kde version.
You could also try the binary beta
yaourt firefox-beta-bin
which will install alongside of the firefox ...not sure if it will for the firefox-kde as I stopped using firefox-kde a long time ago(did not work good for me).
HTH...
[/OT]
Thanks but this has been going on for years ...in windoz too tho' not as dramatic. I'm 90% certain it is cache related. After a while, sometimes, for some websites, the Back|Forward will work as it should(well almost: only a second delay).
c-ya
My set up is updated to 2017-04-02 with firefox kde. But video playback issue is happening for chromium also.
On 1st April i tried playing videos from April Fool's day prank thread started by philm and it did not work. I thought that's how it is supposed to be. youtube videos or i must say html5 playback is not happening on my KDE plasma setup.
I shall start a new thread for this issue else current thread wud go off-topic.
Fixed this problem by following steps
In konsole type
kdesu dbus-launch konsole
In new Root konsole window execute below commands in exact order
pacman -Rndd ffmpeg
pacman -S ffmpeg
pacman -S --asdeps ladspa
I know i am technically necrobumping, but otoh this Tutorial is still being actively referenced in the forum, eg:
Therefore, i thought i might inspect some of the OP recommendations in my FF-Nightly Version 76.0a1 (2020-03-22) (64-bit). This is not exhaustive; i just tried a few, but a high proportion of those i tried, do not have a matching pre-existing flag already in my FF-N's about:config, eg:
browser.cache.use_new_backend
network.http.pipelining
So maybe these ones simply need manual creation [though it was not mentioned for them, unlike an earlier one] & thence would still work... or maybe they're now superseded in contemporary FF? 
Wrt Graphics, mine simply says
Compositing WebRender
...so maybe the OP advice is now superseded [not saying it is, i dunno]?
IMO Tutorials are wonderful when fresh out of the oven, but become a double-edged sword breadknife with the passage of time.
Three years ago was pre-Firefox Quantum wasn't it? So yes, some options will have changed or been removed. Good warning for folks tempted to go hunting.
Would it be appropriate to tag this thread as outdated?
It would be more appropriate to bring it to @BS86 attention and let them decide to either update it or self-flag.
That said, it is a Wiki post so anyone can edit it.
Afaik iirc tla, when it was written FF was still with the [IMO ghastly] Australis paradigm [ugh, hated that]. Again afaik but happy to be corrected, the change to Quantum also changed various flags [hate myself for using the chromium terminology here, but it's quick & dirty] which furthermore, as Quantum itself has matured has further changed many flags.
Somehow IMO tutes like this need some kind of sunset-clause [or maybe a validity-canary, teehee]...?
Just checked some old bookmarks. Q arived with FF 57, which was 2017, maybe June'ish? Hmmm, more like November apoparently...
I added a note.
Not sure if the topic should be kept for some historic purposes or if someone wants to check if the commands still help. I edited the starting post to at least tell the facts at the beginning but I would have no problem with setting it private only / hiding it from the public / deleting it.
Personally, I reverted all the manual changes not long after the Quantum update and don't have any motiviation on trying them again as Firefox is definitely not slow or laggy at all since Quantum arrived.
I think the amended 1st post's banner
This tutorial was created pre-Quantum (FF57). Some commands might still help, but most won't. Consider this tutorial outdated and obsolete!
is lucid & explanatory, ie, excellent.
From my perspective, re my heinous necrobump, i was simply anxious to help illuminate that whilst once accurate, anyone post-Australis trying to blindly apply some of those settings now might end up "disappointed" or worse. Also, the banner might now stop other Manjaroos cross-referencing this thread to noobs.
It is really quite simple to fix such issues with FF or any modern browser:
Well prune the excess number of Add-ons and Extensions.
Especially those that are buggy or utterly useless.
Don't install excessive numbers of those things in the First Place!!!
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