Open Bug 1433848 Opened 3 years ago Updated 2 years ago

Severe scrolling performance regression after Skia 59 update when <textarea> visible in document containing border-radius styling


(Core :: Graphics, defect, P3)

60 Branch



Tracking Status
firefox-esr52 --- unaffected
firefox-esr60 --- wontfix
firefox59 --- wontfix
firefox60 --- wontfix
firefox61 --- wontfix
firefox62 --- fix-optional


(Reporter: ke5trel, Assigned: lsalzman)


(Depends on 1 open bug)


(Keywords: regression)


(3 files)

1. Install Reddit Enhancement Suite (RES) extension.
2. Go to, login and open reply box to a comment.
3. Fill reply box with text so that it overflows and scrollbar is visible. 
4. Make sure reply box is focused.
5. Scroll page.

Scrolling is very slow with large stutters while the reply box is visible. See attached performance recording and screenshot.

RES puts a border around every .comment with border-radius: 3px by default, disabling this border radius makes the problem go away. Changing to cairo also fixes the problem.

Regression window:

Regressed by: Bug 1340627

Ubuntu 17.10 (Xorg)
AMD integrated GPU
Updating Skia in 60, let's see what that does do this test case.
Assignee: nobody → lsalzman
Attached file example.html
New STR with simpler test case:
1. Load attached example.html.
2. Focus text box.
3. Scroll page.

Note bad scrolling performance when a focused overflowing <textarea> is visible inside an element with border-radius > 1px and overflow:hidden. Scrolling improves after a while but degrades every time the <textarea> is refocused.
Enabling WebRender on latest Nightly 62.0a1 fixes this performance problem for me on Ubuntu 18.04 with AMD BARTS.
Depends on: webrender
Depends on: fixed-by-webrender
No longer depends on: webrender
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