Open Bug 1720236 Opened 4 years ago Updated 1 year ago

Certain articles on lanacion.com.ar slow down Firefox a lot, or cause it to become unresponsive if read on inoreader.com (RSS reader)

Categories

(Core :: Performance: Responsiveness, defect, P2)

Product:
Core
Component:
Performance: Responsiveness
Version:
Firefox 89
Type:
defect

Tracking

()

Project Flags:
Performance Impact medium

People

(Reporter: imdb456, Unassigned)

References

Details

(Keywords: perf:responsiveness)

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:89.0) Gecko/20100101 Firefox/89.0

Steps to reproduce:

  1. Enter to https://www.lanacion.com.ar/sociedad/coronavirus-en-la-argentina-confirman-480-muertes-y-14989-nuevos-casos-en-las-ultimas-24-horas-nid12072021/

  2. For read the same article in inoreader.com, enter with the following information:
    User: Disposable.Ino.Reader@yandex.com
    Password: Disposable.Ino.Reader

Go into the "Stars" folder (where there are only eleven articles that I put there on purpose), and move from one article to the next (you can use the J or N key for next article, and K for previous), until reaching the article titled "Coronavirus en la Argentina: confirman 480 muertes y 14.989 nuevos casos en las últimas 24 horas"

If you enter the folder called "La Nacion", you can get an idea of ​​how it usually works.

Actual results:

  1. Reading in lanacion.com.ar, long delay to finish loading the page, much longer than Brave and Edge (Chromium-based Edge).

  2. Reading the same article in inoreader.com, at one point Firefox stops responding, sometimes before and sometimes after reaching the article that creates the problem.

Expected results:

Less delay. Firefox should be always responsive.

Component: Untriaged → Performance
Product: Firefox → Core
Whiteboard: [qf:p2:responsiveness]

dthayer reproduced this - we're seeing a lot of checkerboarding on this site. He collected a performance profile: https://share.firefox.dev/2W5v6gk

Performance Impact: --- → P2
Keywords: perf:responsiveness
Whiteboard: [qf:p2:responsiveness]
Priority: -- → P2
Component: Performance: General → Performance: Responsiveness

The severity field is not set for this bug.
:mstange, could you have a look please?

For more information, please visit BugBot documentation.

Flags: needinfo?(mstange.moz)

I can also reproduce long checkerboarding on that page. I have not attempted part 2 of comment 0.

I think the page keeps Chrome busy for a similar amount of time, but Chrome doesn't show checkerboarding because it caches a larger display list than we do.

I also did a JS comparison report and the biggest difference was in an anonymous function which calls a getter lots of times.
Firefox: https://share.firefox.dev/42RsBNx (3443 samples)
Chrome: https://share.firefox.dev/3GBIgJa (1352 samples, 2.5x faster)

Severity: -- → S3
Status: UNCONFIRMED → NEW
Ever confirmed: true
Flags: needinfo?(mstange.moz)
Depends on: 1962778
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