Bug 232673

Summary:

CSS outlines in contenteditable elements causes performance issues

Product:

WebKit

Reporter:

Brian Kim <briankimpossible>

Component:

HTML Editing

Assignee:

Nobody <webkit-unassigned>

Status:

NEW

Severity:

Normal

CC:

briankimpossible, loginwebkit, megan_gardner, simon.fraser, webkit-bug-importer, wenson_hsieh, zalan

Priority:

Keywords:

InRadar

Version:

Safari 15

Hardware:

Mac (Apple Silicon)

OS:

macOS 11

Attachments:

Description	Flags
Safari Devtools timeline dump	none

Brian Kim

Reported 2021-11-03 11:15:45 PDT

Created attachment 443215 [details] Safari Devtools timeline dump Typing in contenteditable elements is slow when using the default focused outline CSS rules. Steps to reproduce: 1. Go to https://www.slatejs.org/examples/plaintext 2. Inspect the contenteditable element and disable the `outline: none` style. 3. Try inserting many newlines using the Enter key. 4. When there is a visible outline, you should see noticeable lag and frame drops as the document size increases. 5. This lag does not exist when the `outline: none` style is re-enabled. I’ve attached a timeline export from Safari Devtools. The important detail is that in the frames view, Devtools reports that time is spent in Other (not Layout, Painting, Scripting). I do not have the ability to investigate further at this time.

Attachments
Safari Devtools timeline dump (29.27 MB, application/json) 2021-11-03 11:15 PDT, Brian Kim	no flags	Details
View All Add attachment proposed patch, testcase, etc.

Radar WebKit Bug Importer

Comment 1 2021-11-10 10:16:35 PST

<rdar://problem/85259554>

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