Firefox: Performance in Progress

https://blog.mozilla.org/performance/2021/08/05/performance-in-progress/

by EMM_386 • 5 years ago

287 126 5 years ago

blog.mozilla.org

edoceo2• 5 years ago

I super excited for any new FF stuff but this one mentions a lot of Windows focused (and some Mobile) - I'm over here on Linux where I've still got loads of pages that just lag. Hoping for some multi-platform JS updated soon-ish.

Side note: anyone know of any meaningful updates to Servo? Is dead? It had so much promise (IMO)

lu4p• 5 years ago

Servo is mostly dead the team got laid off

rickstanley4• 5 years ago

Really? Bummer. I hope the community keep a steady pace at development and don't let it die. Having another engine competing with the "titans" of the current web would bring so much benefit (I think and hope so).

The "recent" event[0] with Chrome dev team scared me; they have so much power to change things "at will".

[0] https://news.ycombinator.com/item?id=28055160

happy-dude• 5 years ago

Servo was never meant to be a full engine replacement for mainline Firefox; whatever Rust code could be implemented/useful for Firefox was ported already.

However, regarding Servo specifically, there are contributions on their GitHub[1] and the stewardship of the project is now under the Linux Foundation[2].

[1] https://github.com/servo/servo/commits/master [2] https://blog.servo.org/2020/11/17/servo-home/

azakai• 5 years ago

Servo was never meant to be a full engine replacement for mainline Firefox

I don't think that's a fair summary of the history. There were multiple points of view on this inside Mozilla, and some (including myself) definitely hoped it would be a full engine replacement.

lucgommans3• 5 years ago

Speaking of Firefox performance, does anyone know what introduces pauses in page loading? A page of 900 bytes HTML, with 2 KB of CSS and a 33 KB background image, takes 918 ms to load. Only a third of that is network stuff (DNS resolving, TLS setup, etc.; adding up the 'duration' values). Screenshot of page with loading graph: https://i.snipboard.io/AcqWb4.jpg Notice the huge gap between HTML loaded and starting to load CSS, for example, where it does not appear to be doing or waiting for anything.

Seeing the title and initially glancing at the drawing where it says "reading XUL.dll" I thought they addressed this, as I noticed this problem a while ago and I figured it was something about this multi-process browser experience having to load everything anew or constantly do inter-process communication, but the post is actually about various other performance issues. Does anyone know what's up with this one?

Just to be clear, I'm not saying Firefox is slower than browser X or anything. I just happen to notice this in Firefox because I'm a Firefox user.

tech-no-logical• 5 years ago

I have no idea what causes it for you, but I see this : https://i.imgur.com/KEWYqIW.png

(ff 91.0)

lucgommans3• 5 years ago

Which OS is that on? Mine was on Linux, perhaps that makes a difference. Also I have a rather crappy cpu (i5-8250U); for you I still see the gaps even if they're smaller (both in absolute terms but if I'm seeing it correctly also in proportion to network loading time), so perhaps a faster cpu helps as well.

roomey• 5 years ago

Try it in safe mode with your plugins disabled, it will at least show you if it is vanilla behaviour

lucgommans3• 5 years ago

Good point, should have thought of that. I have a bunch of things open where I don't want to reload the page so restarting in safe mode is a bit tricky now, but unless someone happens to know the exact answer I can try this on the weekend and perhaps narrow it down, thanks :)

btdmaster• 5 years ago

about:processes is also a decent way to pinpoint the most impactful extension.

Edit: my bad, I meant to say about:performance.

pabs3• 5 years ago

Some issues are caused by the current profile, so it is a good idea to use a temporary profile for testing weird bugs. Here is a script to automatically create and clean up a temporary Firefox profile:

  $ head -n-0 ~/bin/firefox-tmp-profile 
  #!/bin/sh
  # Workaround for missing feature:
  # https://bugzilla.mozilla.org/show_bug.cgi?id=1604376
  set -e
  dir="$(mktemp --tmpdir --directory firefox-tmp-profile-XXXXXXXX)"
  cleanup () { rm --recursive --force "$dir"; }
  trap cleanup EXIT
  firefox -no-remote -profile "$dir" "$@" || true

koyote• 5 years ago

I am seeing similar bad performance on Chrome on my fully loaded enterprise laptop.

I think it's that background pattern and Firefox might be lying to you, or at least in Chrome the pattern is what eats up all the rendering time.

bzbarsky• 5 years ago

The really interesting part is the huge gap between loading the CSS and starting the load of "patternbg.png", which is linked to by the CSS. When I load https://lgms.nl/ locally, I see the CSS finish loading at the 397ms mark in the overall pageload and the image load get queues at the 411ms mark, which is more like what I expected.

My best guess is that there is some extension involved that takes a long time to process attempted fetches and decide whether to allow them or not.... It would be interesting if the timeline included "we are ready to go fetch this and waiting on extensions to make up their mind" bits.

jml7c5• 5 years ago

Have you tried using the profiler? It will give you a lot of detail. It's under the "performance" tab on the dev tools.

gorhill• 5 years ago

See if disabling the setting "Uncloak canonical names" in uBO helps.

There are similar loading delay issues as you describe when uBO has to resolve DNS names if you are behind a proxy.

miduil• 5 years ago

Thank you a lot! I just tested it on my Android phone and finally I don't have to wait seconds before I see any page content. I was really puzzled what caused this problem for a while.

BeefySwain• 5 years ago

What does this do?

mmis10002• 5 years ago

Use the new https://profiler.firefox.com/ .

It can literally tell you what can go wrong inside the whole Firefox architecture (Includes network, webtension, firefox internals, page scripts and so on).

My personal guess about it is about extensions, did you retry it again in safe mode?

And if you suspect it is a issue in firefox itself, you can upload the profile and open a bug at https://bugzilla.mozilla.org/home , so someone more familiar with Firefox can investigate it.

Too• 5 years ago

Wow, good stuff. But why is such a fantastic tool hidden from the default developer toolbar?

aspartate• 5 years ago

Meanwhile I feel like on my Linux laptop Firefox has only been getting slower and slower every year. Perhaps the fact that I'm using a GeForce as my primary GPU can have something to do with it? I read it causes some problems with WebRender. Anyway it's sad to see Chromium being way snappier on my machine, I have to use it for meetings because just after a couple minutes audio in FF starts to stutter intolerably.

Saris• 5 years ago

Make sure HW acceleration is working, I've noticed firefox on linux seems to have it disabled more often than it should.

arp2427• 5 years ago

Some time ago I removed a whole bunch of packages from my system I hadn't used in a long while, and turned out I also accidentally removed the "pciutils" package which turns out to be a runtime dependency for Firefox's hardware support.

Without it, regular things were significantly slower, especially if images were involved, even on simpler sites. Just installing pciutils again instantly made a huge difference.

TingPing2• 5 years ago

Quite a few of Firefox's recent gpu changes do require Wayland and open drivers. Nvidia might get whitelisted at some point.

vehemenz• 5 years ago

I'm not sure when it happened, but in the past few months I started noticing slower responsiveness in Chrome. Which is weird, because historically that was the type of thing I tolerated in Firefox.

It looks like Firefox is the new speed champ on MacOS, at least among serious browsers. If Safari's WebExtension ecosystem actually progresses with Safari 15, that may be worth another shot, too.

the_jeremy• 5 years ago

I have the opposite behavior on my macbook pro - Chrome can handle videos at 2x speed just fine, but Firefox will stutter or go sound-only for a few seconds if it heats up at all.

kibwen2• 5 years ago

On my Macbook, bizarrely, it's Safari that freaks out when watching videos at 2x speed, whereas Firefox handles them fine.

Tagbert• 5 years ago

Video handle really varies depending on how it was encoded and whether there is a hardware decoder available or not. YouTube is highly tuned to work well with Chrome and vis versa.

cwizou• 5 years ago

It's definitely not slow on macOS but for some reason the UI font just looks wrong to me on macOS and I can't quite put my finger on it.

The font doesn't look system (maybe it is), and every element is a tad too small. Spacing between letters is also more cramped that on every other macOS app.

I know doing cross OS development is hard but to me this is what's stopping me to move full time from Safari to Firefox on mac, the UI font just looks wrong (despite all the things I don't like in Safari like not having uBlock Origin and having to rely on a subpar extension with an app, or the terrible new Monterey UI).

Antrikshy2• 5 years ago

My gripe with FF on Mac is the lack of support for autocorrect. While I can live without autocorrect, this also means my text expansions (stuff like shrug -> ¯\_(ツ)_/¯) don't work in FF but work in basically any other text bo, since they use the same text replacement mechanism.

jeppesen-io• 5 years ago

I've noticed the same with Chrome feeling laggy comapred to Firefox on Linux and Android

robertoandred3• 5 years ago

Based on their cartoon, looks like the problem is Windows' weird way of conflating applications and application windows.

floatingatoll4• 5 years ago

Could you talk more about that way?

robertoandred3• 5 years ago

If you open an application when it's already open, Windows creates a whole new instance of the application instead of just switching to the already-open application.

wnevets• 5 years ago

I'm the opposite of someone who keeps tons of tabs open, I'm constantly closing and reopening the browser through out the day. One of main reasons why I started using Chrome in the first place all of those years ago was the start up speed. I know Firefox is much better today at this in the past but any improvement would help me switch full time to FireFox.

SimeVidas• 5 years ago

On my MacBook Pro, from the moment I launch Edge, it takes 10 seconds for the window to appear. Sounds like Microsoft could use this optimization.

godelski• 5 years ago

I turn my computer off frequently and FF launches instantly when I open it. Just as fast as any other program (and I'm a tab hoarder).

Though the number one reason I have FF instead of Chrome is that FF Mobile allows ad blocking. So I can have ad blocking across my browsers, send tabs, and keep consistent plugins. The anti-tracking and privacy features are also a great plus.

starik36• 5 years ago

That is precisely the reason I switched back to Firefox after all those Chrome years.

The Firefox startup is pretty much instant. Chrome starts fast as well, but there is a moment, when it's just a blank window that I can't do anything with.

Firefox opens instantly to a usable window with the cursor blinking on the address bar.

systems• 5 years ago

firefox needs a better support forum i like firefox a lot, more philosophically .. independent, open source, rust

anyway, a while ago, firefox starting crashing on me like crazy

and tried to get support from there https://support.mozilla.org/en-US/questions/

but after a while i just gave up, they need to setup a discourse forum or something, some place more interactive

mburns• 5 years ago

https://discourse.mozilla.org/

arp2427• 5 years ago

/r/firefox on Reddit can be helpful.

causality04• 5 years ago

I wish Mozilla spent ten percent as much time un-fucking their old features as they do coming up with new ones. Firefox Mobile still doesn't have a user agent switcher. The "tab closed" popup still blocks you from opening the next tab. There's still no option for moving the New Tab button to the top of the screen.

taeric• 5 years ago

That "tab closed" pop-up is maddening. I've mainly assumed I was just doing it wrong, it is so bad.

temp0826• 5 years ago

Does "request desktop site" not change the user agent?

rickstanley4• 5 years ago

It does change but it only removes the "mobile" part from user agent (through sniffing). But I think he's referring to a broader usage, for instance: MS Teams only works on Chromium-based browsers and Safari, so user agent change façade comes in handy for this.

causality04• 5 years ago

Not fully. It requests a desktop layout but sites still know you're on a mobile browser, hence sites that explicitly block mobile browsers will show the same "this page only viewable on desktop" message. Actual user agent switcher extensions don't have that problem.

floatingatoll4• 5 years ago

“Tab closed” popup?

deadbunny3• 5 years ago

On Android.

LanternLight83• 5 years ago

Yes! When attempting to close the last two tabs in the vertical tab list, one after another, the "Tab Closed ↩" popup of whichever tab you close first will arise at the bottom of the list and obstruct the close button ('X') of the remaining tab, for it's full 3 second duration. Hence, to close the last n tabs, you must close the second-to-last tab n - 1 times, and then wait those 3 seconds to close the last tab.

j1elo• 5 years ago

A video is worth 29.97 pictures:

https://twitter.com/j1elo/status/1419907944456638489

phreack2• 5 years ago

More importantly, you can't read long text in small copy by zooming in without having to scroll sideways in FF mobile. That's just such an obvious UX problem it's unfathomable how it hasn't been addressed yet. There's been an issue open on this problem for about 10 years already.

frosted-flakes2• 5 years ago

What do you expect it to? Wrap the text? Do any mobile browsers work like that? Zoom doesn't change the viewport size.

rickstanley4• 5 years ago

You can swipe the "Tab closed" popup to dismiss it.

edoceo2• 5 years ago

Thank you!

causality04• 5 years ago

Why should I have to? Why does it have to pop up in the exact damn place the user is most likely to tap?

deadbunny3• 5 years ago

My biggest bugbear on Android is the 1 min+ to load the first page if FF has been closed for a while.

neogodless• 5 years ago

How long does Firefox have to be closed to reproduce this issue?

clcaev• 5 years ago

Here is another usability issue that begs attention: when you attempt to type in the search text box of the "new" tab, it jumps focus to the URL bar.

https://bugzilla.mozilla.org/show_bug.cgi?id=1707701

ajnin2• 5 years ago

I get the same kind of fascination reading those comment threads as one would get watching a train wreck. To multiple users telling them that their stuff is broken, they reply that this is their actual intent. The thought that maybe there might be a flaw in their design does not cross their minds an instant. "Am I out of touch? No, it is the users who are wrong."

I particularly love the suggestion to use https://ideas.mozilla.org/ to submit feedback, as if that change went through the same procedure, and as if they didn't moderate away any suggestion that they don't like.

And yet they still don't realize that this "we know better than the users what's good for them" attitude is killing their product.

shdufuiddueuu• 5 years ago

Tbh as much as I'd like a user agent switcher I really like the new stuff too since a lot of it is aimed at convenience out usability. Blemishes aside it's quickly become my favorite mobile browser to use (having already tried Chrome, Edge, Brave, and a few others.

andrepd• 5 years ago

They removed a proper tablet interface with tabs etc to simply using the phone interface.

cycomanic3• 5 years ago

Maybe it's different on nightly but for me the closed tab notification does not block anything.

I can't speak for putting the new tab button to the top, but I was asked if I want the URL bar at the bottom or top when installing Firefox for the first time. For me having the controls at the bottom is one of the killer features, because I can just use my thumb to do things.

c7DJTLrn• 5 years ago

I remember years ago when Firefox Quantum boasted of lofty performance improvements only to get pummelled in just about every benchmark against Chrome. I still check out Phoronix's benchmarks now and again and Firefox is consistently behind. Make whatever excuses you will, but the numbers don't lie.

dblohm72• 5 years ago

You're putting way too much emphasis on benchmarks vs real-world usage, IMHO.

hfjtbtbfjfj• 5 years ago

I use highly interactive websites, like bitcoin exchanges.

They work terribly in Firefox. I don't know if it's because Firefox is slow, or if because devs don't test in Firefox. Either way, even if Firefox is my main browser, I learned that I need to use these sites only in Chrome.

YouTube and most other video sites also are very slow in Firefox and many times the other sites don't work at all, video doesn't start, ...

roca3• 5 years ago

Quantum worked! Firefox did get a lot faster. It's just that Chrome and Safari are also getting faster. It's an endless race.

maskros• 5 years ago

I'll gladly suffer a little bit worse rendering performance and have images resized with good rescaling filters than the blurry pixelated mess that Chrome renders whenever the zoom isn't exactly 100%. It's easy to do well on benchmarks when you sacrifice rendering quality.

And of course there's no way to even ask Chrome to render images with a decent resampling filter...

hiyer• 5 years ago

I'm not sure if benchmarks reflect real-world performance with adblockers and other extensions installed. I've been using FF (nightly) as my daily driver on Linux and Mac for years and I don't see any perceptible difference in page loading times compared to Chrome. The only area where I find Chrome noticeably faster is in starting the application itself, but since I rarely close the browser this is not something I see often.

Unfortunately corporates seem to be ignoring Firefox entirely - last 2 companies I worked at, their webapp worked only in Chrome. So I'm forced to use Chrome (or Chrome-ish browsers like Brave) also on a daily basis.

the_duke• 5 years ago

I switched back to Firefox from Chrome a few years ago after their Quantum efforts landed. Both to get out of the Google trap, and because it was clearly the fastest browser for common use, except on certain Javascript heavy pages.

But over the last year or so, performance has continually degraded to the point were I'm upset and resort to Chrome more often (Ungoogled Chromium [1], to be precise).

I guess Specter mitigations and site process isolation might be related, but this does not make me happy...

(this is on Linux/Wayland)

[1] https://github.com/Eloston/ungoogled-chromium

roca3• 5 years ago

Maybe there's something wrong with the Firefox install on your system. On my Linux laptop it keeps getting faster.

ajnin2• 5 years ago

These are some good changes. Perceived performance is very important for a program you use many times per day. One of my long time complaints is that with Chrome, when I want to search for something I'll often ctrl-N to open a new window and then type my query. Even if it takes a little bit of time to show the window my query will be right there in the search bar. With Firefox, those keystrokes are lost. I hope this fixes that.

nyanpasu642• 5 years ago

For as long as I can remember, Firefox has always been janky and slower than Chrome at moving tabs in and out of windows.

Dragging a tab doesn't always create a new window, sometimes it acts as bookmarking if I drag it into the tab bar, sometimes (on Linux) it acts as drag-dropping the tab into another app like Discord and fails to open a window.

Dragging a tab out of a window doesn't create a new window until you release the mouse, so it feels unresponsive, and you don't know whether you'll get a bookmark or tab or nothing at all. And dragging the last tab out of an empty window doesn't close the window to allow me to see what windows lie underneath.

And in the past (not sure now) I've noticed that dragging a tab a few pixels downwards would create a new window, when I meant to click or reorder a tab.

arp2427• 5 years ago

And in the past (not sure now) I've noticed that dragging a tab a few pixels downwards would create a new window, when I meant to click or reorder a tab.

I've had this problem for a long time as well; it's very hard to reliably reproduce too. I ended up finding some about:config setting to just disable this entire feature, and my life has been better since.

jimbob45• 5 years ago

The first one is embarrassingly stupid. The real solution is a splash screen, which was invented decades ago. Instead, they just lie to you with a non-functional window rather than lying to you by pretending that your system is doing nothing.

Moved back to Chrome today btw. Couldn’t handle YouTube full screen taking 10 seconds to expand and collapse on Firefox. Sure wish Mozilla would hire some competent devs.

kibwen2• 5 years ago

Instead, they just lie to you with a non-functional window rather than lying to you by pretending that your system is doing nothing.
Moved back to Chrome today btw.

I find this amusing, as Chrome was the pioneer of this trick.

nickstinemates2• 5 years ago

What kind of hardware are you running that it takes 10 seconds to do a video full screen?

Genuinely curious. My low powered raspberrypi running at 1080p does better than that.

cycomanic3• 5 years ago

You're kidding me! Splash screens are the worst solution for this (actually for anything).

1. They often sit on top of everything so I can't continue working on another document for example when opening a large application (I often open apps but continue working on something else) 2. The mess up window management, because the don't have the window class and name of the main app. So when I set window management rules, I have to set an additional on just for the splash screen (made more difficult because it's only there temporarily). 3. The only information they provide is that the app is starting. Well yes I just opened it. Better show an empty window, at least that avoids 1 and 2.

ohgodplsno• 5 years ago

Moved back to Chrome today btw. Couldn’t handle YouTube full screen taking 10 seconds to expand and collapse on Firefox. Sure wish Mozilla would hire some competent devs.

Right, don't blame Google that purposefully slows down Firefox on half their websites.

arp2427• 5 years ago

It's not a bad trick, as it presents you the UI. It will take you a bit to actually respond to the change of the window opening and moving your mouse or whatnot to do whatever you want to do, and this "human delay" time can be used for Firefox to load fully.

Slash screens, on the other hand, are basically just useless and don't add anything beyond an indication of "the app is loading", but the hourglass mouse cursor (or whatever it is on Windows these days) tells you that already.

vzaliva• 5 years ago

Since I switched to Firefox I have to restart it every 3 days as it gets slow. All debugging suggestions start with "disable all plugins." But this is not practical. We practically live in our browsers nowadays. Without my ad blocker, password manager, and grammar checker I will be severely handicaped. I wish there is a way to debug the situation without resorting to disabling plugins. Perhaps have access to some per-plugin metrics.

lamontcg• 5 years ago

For me that seems to be new behavior. I used to be able to keep it open for weeks without issue, but within the past month or two I've started having to restart it all the time (MacOS).

spartanatreyu• 5 years ago

If you're using "ublock origin" as your ad blocker, then it'd have to be your password manager or grammer checker plugins slowing you down.

Either that, or you're keeping a page up that has a memory leak so it wouldn't matter which browser your using.

Does it go back to it's old speed if you open a blank page then close all other tabs and wait 10 seconds?

drran• 5 years ago

Look for the problem at `about:performance` page.

alphabet9000• 5 years ago

wish they would let users completely disable checking for updates. and get rid of only allowing 'signed' extensions. my guess is that will never ever happen

elktea• 5 years ago

for some reason I thought XUL was dead and gone, with the UI now coded in html and js - wonder if they can further improve loading by removing XUL in the futre

dreamcompiler• 5 years ago

Exactly my first thought. For the last few years Mozilla has been beating the "XUL is dead" drum. What's up with this?

TingPing2• 5 years ago

It is dead, just slow to rewrite everything.

up6w6• 5 years ago

As someone that doesn't have last generation hardware, the performance still matters - I really hope they did it this time.

Cool benchmarks: https://arewefastyet.com

nyanpasu642• 5 years ago

Previously, when a Firefox user encountered a page that had a script that ran over a certain timing threshold, you would see a warning message that looked as follows:

I'd appreciate if the "Stop It" button actually worked, instead of the page and JS engine remaining hung for several seconds afterwards.

tnzk• 5 years ago

I don't know if it is related to this article, but a month or two ago, I found screen sharing with WebRTC (specifically getDisplayMedia) on Firefox have been suddenly notably improved. I read through release notes at that time but there seemed no changes around it, except improvements for WebRender on Linux (whereas I and my colleague use FF on Mac).

If one of the contributors named in the article involved in it, I appreciate greatly since it significantly improved our remote-work environment.

dartharva• 5 years ago

I'll shift to Firefox in a heartbeat if they fix their horrendous font rendering on Windows.

godshatter• 5 years ago

When I was reading this, and the author mentioned XUL.dll taking a long time to load I was assuming the blog would veer into a discussion about what can be done to refactor that code to make XUL.dll smaller. Can it be broken into separate DLLs, with the core portions loaded first? Is there a better design that could be used? But, no, their solution was to show the windows soonest. That's nice, I guess, but it didn't solve the problem. It just solved the user's perception of the problem. It actually increases the load time, so now you have an unusable window for a longer period of time. That's one of my pet peeves - don't give me an interface until you're ready for me to start clicking on things.

WorldMaker• 5 years ago

XUL is the name of Mozilla's old UI language [1]. They've been in the long process of moving UI pieces from XUL into HTML5 (such that the Browser's UI controls use the same renderer as the Browser's contents). One key piece of that was disabling the ability for extensions to use XUL a while back that caused a lot of churn in Firefox extensions.

The impression from that is that they want to entirely get rid of XUL.dll at some point in the future.

[1] https://en.wikipedia.org/wiki/XUL

wolpoli• 5 years ago

I was actually surprised that the author didn't try to solve this by preloading Firefox on start up.

footlose_3815• 5 years ago

They ignore the crap UX changes over the last months, like spacing out the bookmarks in your folders. WTF were they thinking?

naikus• 5 years ago

Over the past iterations of Firefox (mobile), especially since they launched their new UI, I've noticed the performance of features such as CSS animations, etc. have particularly degraded. I have two versions on my Moto X4, Firefox 68 and the new Firefox 92. I use both to test some of the web apps I develop and to my surprise the older version of Firefox performs much better! There's a noticeable jank on the web app (transitions, animations, etc.) on the newer version. The browser itself is much slower than the older Firefox 68. Frankly I don't see any performance improvement.

Firefox: Performance in Progress

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