1. 2

    Everybody says it’s fast, and pages certain do appear the get rendered faster, but CSS variables and JS events run so slowly now that things I have built that used to be silky smooth animations in older FF (and every other browser) are now showing up as slideshows in FF Quantum. What a total piece of garbage!

    Here’s a video I recorded a few moments ago of the same page in the new FF and in regular Safari - for the record, it used to look like Safari’s example in pre-Quantum Firefox: http://staticresource.com/new-ff.mp4

    It’s running so slowly, I’m probably going to get bug reports for my software because of how bad the new FF sucks, and what can I tell them? Downgrading would fix performance, but is never recommended for security.

    1. 11

      Interesting. What machine is this running on? I tried it on mine and couldn’t replicate the effect. Runs smoothly.

      1. 1
        • MacBook Air (13-inch, Mid 2011)
        • Proc: 1.7 GHz Intel Core i5
        • Mem: 4 GB 1333 MHz DDR3
      2. 3

        Looks great here on macOS, I can’t reproduce your issue either. As @skade said, any information on the machine itself would be appreciated, happy to try and help diagnose.

        1. 3

          I get the same thing on a 3Ghz i7 Macmini7,1. Not sure how that particular demo performed in pre-quantum firefox, though.

          1. 4

            Regardless of performance pre-quantum, you can help us investigate if you swing by on IRC at irc.mozilla.org #developers and ask for help in profiling a specifically slow website. Folks will show you around if you’re a bit patient with uss

            N.B.: most Devs are in Pacific Time (utc-8 O think)

            1. 2

              Also, couldn’t find anybody in #developers on irc.mozilla.org - are you sure that’s where you meant to send me?

              image of IRC channel list

              1. 4

                The channel does not show up on that list, probably due to a channel mode (+s).

                It’s #developers, it’s there and there’s around 600 people in right now.

                1. 3

                  For those wondering if anything good ever came out of this thread.. innovati dropped by and we ended up with at least a couple useful bug reports & test cases, and devs are looking into it :-) So thanks a lot.

                  https://bugzilla.mozilla.org/show_bug.cgi?id=1417970

                  https://bugzilla.mozilla.org/show_bug.cgi?id=1417991

                  1. 3

                    Thanks for your help DuClare! Hopefully (if they have time, and if they find the bugs) they can fix these and be on par with previous releases of their own browser, and also join other browsers in their performance ^_^

            2. 3

              It ran as smooth as could be previously, none of the demos I’m talking about are particularly computationally expensive and run just fine on low end hardware, but it feels like new FF is throttled or something, it’s not just jumpy it’s a downright slideshow

            3. 1

              Compare this page in new FF to any other browser: https://s.codepen.io/tomhodgins/debug/egWjBb

              Should this little amount of JS turn a modern browser into an absolute slideshow?

              function update(e){
                var x = e.clientX || e.touches[0].clientX
                var y = e.clientY || e.touches[0].clientY
              
                document.documentElement.style.setProperty('--cursorX', x + 'px')
                document.documentElement.style.setProperty('--cursorY', y + 'px')
              }
              
              document.addEventListener('mousemove',update)
              document.addEventListener('touchmove',update)
              

              It updates 2 variables on mousemove and touchmove - that’s it! There’s literally nothing else going on in this demo :/ It worked fine in FF until this new version.

              1. 3

                This is working very smoothly for me. Running firefox 57 on arch linux.

                1. 1

                  Thanks for having a peek :3

                2. 2

                  What version did you run previously? 56 or something older?

                  I’m being told there’s event throttling in nightly which should reduce excess updates and thus improve performance. This doesn’t explain why performance should have regressed in 57. I honestly can’t see much of a difference between 56, 57, and nightly.

              2. 2

                I can see a similarish slowdown of the animation on my version of FF (58.0b1 (64-bit) dev edition on Windows 8.1). Granted, I’m running on an older bit of hardware. (a 4-core i5-2400 running up to 3.1GHz, 8GB of memory). Chrome on the same machine runs the animation smoothly

                Overall, on older hardware (2010-12 era CPUs), FF 57+ seems to have issues where a heavy page seems to be able to contest rendering on other pages, at least that’s my guess. However, I don’t have a stable repro at the moment.