1334990 - Wikipedia Mobile is especially slow to paint after scrolling

Status: NEW

(Core :: Panning and Zooming, defect, P3)

Description

[Julien Wajsberg [:julienw]]

STR:
1. Open a heavy Wikipedia mobile page.
This is especially true on https://fr.m.wikipedia.org/wiki/Roger_Federer (I reproduce even on Desktop for that one -- although not all the time).
I also see the issue for https://fr.m.wikipedia.org/wiki/Liste_des_pays_et_territoires_par_superficie on Firefox/Android.

2. Scroll up and down.

On Firefox Desktop, when I reproduce (not 100%) I see grey backgrounds that can last up to 1.5 seconds.

On Firefox/Android, I reproduce 100%, I see blurry rendering, more and more blurry (or even sometimes just the graphics without text) as I scroll down and Firefox can't keep up. The "broken" display can last up to 12 seconds, which is not acceptable IMO, especially on such a visited site like Wikipedia.

Phone is Sony Z3C, on Android 6.0.1.

Comment 1

[Julien Wajsberg [:julienw]]

Attachment: On Android

Comment 2

[Julien Wajsberg [:julienw]]

Reproduced on Latest nightly as well as last week's nightly (hence setting affected to 53 and 54).

Comment 3

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

I can repro on the Federer page on my Z3C. Just load the page and fling down to the bottom, it takes a long time to re-render.

Comment 4

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

Fennec Beta is also pretty bad.

Comment 5

[Julien Wajsberg [:julienw]]

Just a note because I've seen the dependencies to bug 1335508: I think the slowness can be reproduced with the same page on Desktop too, just maybe not 100%.

Comment 6

[Julien Wajsberg [:julienw]]

Same issue with https://fr.m.wikipedia.org/wiki/Lignes_de_bus_RATP_de_100_%C3%A0_199#Ligne_169

This page shows a big table displaying a list of bus lines. Because it's a table, it's not mobile friendly, and I have to zoom in to be able to read the information. This means I need to scroll horizontally.

What makes this bug more painful is that it happens when scrolling slowly horizontally too, which makes it really hard to read a line.

I also noticed that sometimes it's not repainted even if the information is ready... because it's painted as soon as I resume scrolling even a little bit.

Maybe that last issue is a separate bug ?

Comment 7

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

Yeah that last issue seems like a separate bug. It might be that we suspend compositing for some reason and then don't recomposite when we get a repaint from the main thread.

Comment 8

[Julien Wajsberg [:julienw]]

Filed bug 1348694 for this last bit.