[acqq]

Yes, for my girlfriend, during some last few months Firefox is much slower than before: she uses it mostly for Facebook and Youtube, she doesn't have any extensions installed by herself (not counting the stuff that is in Firefox because Firefox marketing initiatives, like Pocket) and no adbockers, but Firefox uses so much CPU that it gets completely unusable.

And she is not any extreme Facebook user: she has less than 500 "friends." And she doesn't have big "subscriptions" list in Youtube.

So it's completely opposite of the propaganda: the average user, using the most common sites, is hit to the that much CPU more use that the most common sites are unusable.

So what's going on here? It's just the propaganda machine claiming the opposite of what is actually happening at the moment. They maybe have good goals but at the moment it's worse than, for example, a year ago.

Maybe it's because she doesn't have a newly bought computer, which are the ones used by those who test? And I guess those who test don't use Facebook and Youtube?

I also use Firefox but spend zero time in Facebook and minimal time on Youtube and block Javascript wherever I can, so I don't see the same. But I saw the CPU on her computer staying completely blocked by something Firefox is doing. The only thing I was able to figure out: around 40 percent is spent in kernel according to the task manager. Both cores are used more than 90 percent, and the Firefox is not responsive. She doesn't do anything more than scrolling down her Facebook to see that effect. It's not always that bad, obviously depends on the content on the Facebook, but it's bad often enough for her to see the slowness regularly, and when it really gets stuck to complain to me.

What I personally observe is the pages embedding more linked Youtube videos got to be very slow to even display them. Those are the pages I stumble on occasionally, so I didn't investigate. The second effect I've observed is writing a longer post for HN on Firefox getting much slower (less responsive) the longer the post is. Like writing these words now.

So, dear Firefox people, your product is really SLOWER for me too in the last versions, and not faster. And it is extremely slower for a "normal" user using the "normal" Facebook and Youtube.

(Additionally, I use a number of extensions, and only one will remain available soon when they turn off the support for what they mark as "legacy" extensions. That is really strange decision, deciding to remove the major difference between them and Chrome, becoming just as limited as Chrome is for extensions and wasting the work of most of the extension developers.)

[pcwalton]

> So what's going on here? It's just the propaganda machine claiming the opposite of what is actually happening at the moment. They maybe have good goals but at the moment it's worse than, for example, a year ago.

It sounds like you are hitting some kind of bug. Feel free to file issues about it if it's reproducible; the telemetry should also be automatically reporting the issues you're seeing.

I would like to respectfully suggest that you hitting a bug is not evidence of a "propaganda machine".

[acqq]

Slowdown on Facebook and Youtube up to getting stuck (exactly what I talk about) was reported in some form at least since February this year, e.g. this Reddit:

https://www.reddit.com/r/firefox/comments/5sikxt/firefox_unb...

I've found that link after my GF complained many times, and I've seen the CPU at more than 90% (40% in Kernel) and Firefox stuck after only her visiting Facebook and scrolling down. It was hard even to kill the Firefox. I saw bugzilla entries too. Some quadratic loops for every element, triggering recalculating "everything" even if the result shouldn't change were mentioned if I remember.

What I claim is that on 56.0.2 (the most recent version until tomorrow) is still not better, FF getting stuck and CPU being fully stressed, and that the "subscriptions" can't be the only issue (which is the only scenario that the developers accused if I remember correctly the bugzilla conversations). The computer seeing this at almost 100% CPU and Firefox remaining unresponsive has only two cores, AMD CPU. If it's accidentally "better" on 16-core machine of some developer who doesn't use the mentioned sites anyway, my girlfriend can't change it.

Of course nobody is going to give FF developers her own Facebook access for them to reproduce it.

As for my GF the most of the internet are Facebook and Youtube, I suspect she'll really have to switch to Chrome if it continues. She already did "refresh Firefox" or however it is called now more than once. No change. And she is certainly not an outlier (and regarding the slowdown I see, I type these words on Firefox 57 (I downloaded it after reading other comments about the FTP availability, I see "Stylo true (enabled by default)") on 4 core / HT Intel and typing these last lines is also quite unresponsive and my notebook fan started at maximum even if unsurprisingly for 8 virtual cores I don't see much CPU use on the indicator -- something is still obviously wrong even on the very light site like HN and on the more powerful machine -- I guarantee you I see this only in Firefox and when I use native programming editors everything flies all the time).

[pcwalton]

If it is indeed style recalculation that is causing the problem, then Quantum (57) may well solve the issue, as Stylo both improves the dynamic restyling behavior (the style sharing optimization is more flexible) and accelerates the slow case in which restyling needs to occur from scratch (via parallelism). I can't promise anything without being able to reproduce, of course.

Naturally, like all browser engines, Gecko takes performance on popular sites such as Facebook very seriously.

[DiThi]

Did any of you try FF 57? I also used a lot of extensions, but basically all the ones that mattered to me work again. (For tree style tabs I have to add a bit of CSS in a file to make it not awkward, though)

[acqq]

I've just installed 57 for me. The English Dictionary is gone -- now all the words I type here are with wiggly lines, I see "add dictionaries" but I had the darned dictionary already and what's the use trying to add the same? I don't know what to do next. The extensions are all gone, including the NoScript for which the developer claimed that he's adding support for new Firefox -- I checked noscript.net -- I have had the very last version. The mozilla site writes "Not compatible with Firefox Quantum". Noscript was the most used extension from a dozen I have had.

From the less used ones, as an example I've used "Copy Plain Text 2." Now I see there's a new similar and compatible extension by somebody else I guess, but it's obviously more limited: "Note: WebExtension API does not allow setting Copy PlainText as the default copy function of the browser at the moment, neither does it allow user defined keyboard shorts. Once there are such an APIs, I will add the feature."

Others have no replacements at all, not surprising seeing the limitations even for the simple "Copy Plain Text."

(Edit: regarding performance details see my other posts here.)

It's really as bad as it can be.

It's really bad.

[DiThi]

I was rather asking about performance for your girlfriend.

Regarding addons, I'd say give it time. It's a chicken and egg problem that will be solved with time. I was not expecting to switch until end of the year.

[sp332]

Firefox's Webextensions APIs are much more expansive than Chrome's. They still have an active developer community so the ecosystem will recover quickly.