1313707 - BBC website for Aberfan disaster much slower/jankier in Firefox than in Chrome due to slow image painting

Status: RESOLVED WORKSFORME

(Core :: Graphics, defect, P3)

Description

[:Gijs (he/him)]

STR:

1. open http://www.bbc.co.uk/news/resources/idt-150d11df-c541-44a9-9332-560a19828c47

2. scroll down to the second photo, which has text on top of it and zooms in/out as you scroll

ER:
smooth scrolling/zooming

AR:
much more jank than in Chrome, lots of CPU churn.

Comment 1

[Michelle Funches - QA]

Reproducible
Version 	52.0a1
Build ID 	20161031030202
User Agent 	Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Firefox/52.0

Comment 2

[Kartikaya Gupta (email:[e-mail])]

That photo isn't actually zooming. There's a series of photos and as you scroll they flip opacities so that only one of them is visible at a time. On my Macbook Air (non-Retina) I get about the same behaviour in Firefox as I do in Chrome. No noticeable CPU churn.

Gijs, can you get a gecko profile?

Comment 3

[:Gijs (he/him)]

(In reply to Kartikaya Gupta (email:[e-mail]) from comment #2)
> That photo isn't actually zooming. There's a series of photos and as you
> scroll they flip opacities so that only one of them is visible at a time.

Oh, but the visual effect is one of zooming, is that right? Ie the black-and-white photo with the outlines of people carrying something, with white-ish smoke and backlighting (the second one, after the one of the young boy) visually seems to zoom when I scroll down, and that effect is very stuttery.

> On
> my Macbook Air (non-Retina) I get about the same behaviour in Firefox as I
> do in Chrome. No noticeable CPU churn.
> 
> Gijs, can you get a gecko profile?

https://cleopatra.io/#report=4b28da16bb5a53774b1ae623a51250ce74415fa4

This is on my regular beta profile, no e10s, but I don't use too many add-ons so that shouldn't make much of a difference. Looks like we spend a *looot* of time painting. Maybe it's because I'm also on a retina mac or something?

Comment 4

[Kartikaya Gupta (email:[e-mail])]

(In reply to :Gijs Kruitbosch from comment #3)
> Oh, but the visual effect is one of zooming, is that right? Ie the
> black-and-white photo with the outlines of people carrying something, with
> white-ish smoke and backlighting (the second one, after the one of the young
> boy) visually seems to zoom when I scroll down, and that effect is very
> stuttery.

The visual effect is mostly zooming, but it's actually a series of photos. You can see the smoke shift position relative to the people as you advance through the images which wouldn't happen if it was just zooming. It's not supposed to a seamlessly-smooth transition but I suppose it shouldn't be unnecessarily stuttery either.

> https://cleopatra.io/#report=4b28da16bb5a53774b1ae623a51250ce74415fa4
>
> This is on my regular beta profile, no e10s, but I don't use too many
> add-ons so that shouldn't make much of a difference. Looks like we spend a
> *looot* of time painting. Maybe it's because I'm also on a retina mac or
> something?

Thanks. Yes it does look like most of the time is spent painting. Also no e10s means no APZ, so this isn't an APZ issue. It's just regular painting jank. Quite likely amplified because of retina mac, yes.

Comment 5

[Jet Villegas (inactive)]

Seems worse on Nightly 53 than Firefox 50 on Retina Mac.

Comment 6

[Gregory Pappas [:gregp]]

Reporter, are you still experiencing this issue?

Comment 7

[:Gijs (he/him)]

Perhaps unsurprisingly, I no longer have the same machine as 6 years ago. On my current M1 mac, the site seems to behave fine. I took a nightly profile just in case it flags anything up: https://share.firefox.dev/3YFCDOw .

Comment 8

[Gregory Pappas [:gregp]]

I can reproduce slow image painting as described in comment 0 in builds from 2015 to 2018. It became much faster in this pushlog

Closing as WFM