1700597 - Hovering or scrolling over past editions on https://www.miragefestival.com WebRender is laggy with Webrender software enabled

Status: NEW

(Core :: Graphics: WebRender, defect)

Description

[Timea Cernea [:tbabos][inactive]]

Attachment: Recording of the issue

89.0a1(2020-02-24)

[Affected platforms]:
Platforms: Windows 7/8/8.1

Graphics Cards:
Nvidia Geforce 730
Intel 530, 4600
AMD Radeon HD 6670

[Preconditions]:
Reach about:config and set both gfx.webrender.enabled, gfx.webrender.software - true

[Steps to reproduce]:

1. Launch the Firefox browser.
2. Reach https://www.miragefestival.com/
3. Scroll down to the bottom of the page and hover over fast the oast editions or scroll

Expected Result:
The past animation should be smooth and the hover effect should be instant.

Actual Results:
Hovering fast over them is laggy, always behind 1 step.

Notes:
Not reproducible with Webrender Software disabled nor Webrender disabled.

Webrender Software profiler (repro): https://share.firefox.dev/3rf6U4X
Webrender simple profiler (not repro): https://share.firefox.dev/3sjQmdp

Comment 1

[Raluca Popovici, Desktop QA]

This bug is also reproducible on Ubuntu 18 , Intel(R) HD Graphics 630.

Comment 2

[Jeff Muizelaar [:jrmuizel]]

It looks like the profiles weren't done with the "Firefox Graphics" preset. Here's one that has that:
https://share.firefox.dev/3w5EKgG

It looks like a lot of time is being spent in brush_blend

Comment 3

[Jeff Muizelaar [:jrmuizel]]

Here's a profile with basic: https://share.firefox.dev/3cgMep6. Has lots of time in filters but doesn't seem like things have gone as bad.

Comment 4

[Jeff Muizelaar [:jrmuizel]]

Disabling the svg filter on ".single-archive" improves things quite a bit.
Here's the filter:

<svg xmlns='http://www.w3.org/2000/svg'><filter id='grayscale'><feColorMatrix type='matrix' values='0.3333 0.3333 0.3333 0 0 0.3333 0.3333 0.3333 0 0 0.3333 0.3333 0.3333 0 0 0 0 0 1 0'/></filter></svg>

Comment 5

[Jeff Muizelaar [:jrmuizel]]

Disabling that filter enables a "filter: grayscale(1)" that runs considerably faster but still isn't amazing: https://share.firefox.dev/3ricrIa. I'd guess that the svg filter is so much slower because we're doing multiple passes (for sRGB -> linear conversion and then back)

Comment 6

[Jeff Muizelaar [:jrmuizel]]

It's probably reasonable to add the ability to do sRGB conversion in addition to a filter so that we can take the 3 passes and drop it down to 1

Comment 7

[Jeff Muizelaar [:jrmuizel]]

Attachment: A reduced test case