1423633 - Page full of links scrolls extremely slowly

Status: RESOLVED WORKSFORME

(Core :: Graphics: WebRender, defect, P1)

Description

[Josh Matthews [:jdm]]

Visit https://archiveofourown.org/media/Books%20*a*%20Literature/fandoms#letter-I with the webrender preferences from https://mozillagfx.wordpress.com/2017/11/27/webrender-newsletter-10/ enabled. Scroll up and down the page, and notice how slugglish everything behaves. Disable the webrender preference, restart, and notice how quickly the page responds to scrolling.

Comment 1

[Jeff Muizelaar [:jrmuizel]]

I think this is probably inset boxshadow. See https://github.com/servo/webrender/issues/2145

Comment 2

[Andrew Osmond [:aosmond] (he/him)]

Attachment: Simplified test case, v1

Yes it is the inset box shadow. This test case which just has a single short list, and an inset box shadow, has the same behaviour.

Comment 3

[Andrew Osmond [:aosmond] (he/him)]

(In reply to Andrew Osmond [:aosmond] from comment #2)
> Created attachment 8940252 [details]
> Simplified test case, v1
> 
> Yes it is the inset box shadow. This test case which just has a single short
> list, and an inset box shadow, has the same behaviour.

I should note that for me this test case does not even render correctly with WebRender. The bottom and right lines of the box are missing, and appear as expected when WebRender is disabled.

Comment 4

[Darkspirit]

(In reply to Andrew Osmond [:aosmond] from comment #3)
> I should note that for me this test case does not even render correctly with WebRender. The bottom and right lines of the box are missing, and appear as expected when WebRender is disabled.

The bottom and right lines were fixed by bug 1429411. (I can't say anything about performance.)

Comment 5

[Glenn Watson [:gw]]

I tested this morning and this appears to be running well for me now. There's been some significant optimizations to inset box shadows land in the last couple of weeks.

On my HD4600, it sits at ~6ms per frame GPU time. This is higher than ideal (I would expect we hit closer to 3-4ms on this page long term), but easily within the 16.67ms frame budget for 60 fps.

Josh, can you confirm that this is now running at 60 fps on your machine?

Comment 6

[Josh Matthews [:jdm]]

Agreed.