1636604 - Firefox 76.0 Webrender Scroll Jitter (1920x1080@75Hz) UHD Graphics 620

Status: RESOLVED INCOMPLETE

(Core :: Graphics: WebRender, defect, P2)

Description

[jguo]

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:76.0) Gecko/20100101 Firefox/76.0

Steps to reproduce:

Open any webpage and scroll. There is noticeably more jitter/lack of smoothness compared to Firefox 75.0 or when I disable webrender. This is more noticeable on pdfs and on youtube videos.

Here is a performance profile: https://perfht.ml/2yGi5yn.

Actual results:

After updating to Firefox 76.0, I noticed a lot more choppiness on the scrolling. Especially for pdfs and youtube videos. Disabling webrender by going through about:config and setting 'gfx.webrender.force-disabled' to true reverts back to the expected scrolling behavior from Firefox 75.0

Expected results:

The scrolling should have stayed as smooth as on Firefox 75.0. Now it is noticeably choppier, especially on pdfs.

Comment 1

[BugBot [:suhaib / :marco/ :calixte]]

Bugbug thinks this bug should belong to this component, but please revert this change in case of error.

Comment 2

[Jessie [:jbonisteel] pls NI]

Can you attach the contents of your about:support as a text file? Thanks

Comment 3

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

Also can you check if you see this on the latest Firefox Beta or Firefox Nightly? It may have been fixed by bug 1630781.

Comment 4

[jguo]

Attachment: about-support.txt

Here's my about:support. Also, I just checked am and on 76.0.1.

Comment 5

[Firefox Bug Husbandry Bot]

Because this bug's Severity is normal and has not been changed, and this bug's priority is -- (none,) indicating it has has not been previously triaged, the bug's Severity is being updated to -- (default, untriaged.)

Comment 6

[Jessie [:jbonisteel] pls NI]

jguo, I know you mentioned that this happens pretty consistently on 76 for you with WebRender on - can you share any links to particular pdfs or videos where you really notice it?

Comment 7

[Jessie [:jbonisteel] pls NI]

Glenn, just NI-ing you for awareness

Comment 8

[Glenn Watson [:gw]]

Jeff, there doesn't seem to be any mention in about:support whether DC is enabled or not - shouldn't this build have DC enabled?

Comment 9

[Jeff Muizelaar [:jrmuizel]]

Can you share a specific URL where you see this problem? Also would you be willing to try Firefox Beta 77 to see if it's any better?

Comment 10

[Glenn Watson [:gw]]

The profile provided has per-frame screenshots enabled, which unfortunately have a major impact on the renderer time in the profile. Would you be able to submit another profile with screenshots disabled (in the profiler settings).

Comment 11

[Rachel Tublitz [:rachel]]

S1 or S2 bugs need an assignee - could you find someone for this bug?

Comment 12

[Jessie [:jbonisteel] pls NI]

Without more information from the reporter, it is unclear what action we could take here.

Comment 13

[Jessie [:jbonisteel] pls NI]

Still awaiting more information from the reporter to determine what we can do.