Bug 167561

Summary: Sluggish/slow scroll on some webpages
Product: WebKit Reporter: François Lamboley <webkit.org>
Component: Layout and RenderingAssignee: Nobody <webkit-unassigned>
Status: NEW ---    
Severity: Normal CC: bfulgham, ddkilzer, simon.fraser, webkit-bug-importer, zalan
Priority: P2 Keywords: InRadar
Version: Safari Technology Preview   
Hardware: Mac   
OS: macOS 10.12   
See Also: https://bugs.webkit.org/show_bug.cgi?id=165196
Attachments:
Description Flags
An example of a WebSite with a sluggish scroll (WebArchive and HTML)
none
Same example as previous, without the JS (HTML) none

Description François Lamboley 2017-01-29 07:40:59 PST
Created attachment 300069 [details]
An example of a WebSite with a sluggish scroll (WebArchive and HTML)

First let me apologise in advance for duplicate bugreport if any. In particular this bug might be related to #165196.

Some WebPages (I have attached an example, but I don't know any public site with this problem) have a very sluggish scroll on the latest (late 2016) retina MacBook Pro w/ Touch Bar, when it works fine in Chromium & Firefox.
It is not a problem related to JavaScript as the scroll is as sluggish with JavaScript off.

I've joined the WebPage in two formats (Safari WebArchive & pure HTML).
For both formats, you’ll have to disable JavaScript for the content to stay in the page.

I can join another example of a WebPage with this sluggish scroll if needed.
Comment 1 Radar WebKit Bug Importer 2017-01-29 16:21:49 PST
<rdar://problem/30255300>
Comment 2 Simon Fraser (smfr) 2017-01-30 10:32:17 PST
The attached webarchive and HTML didn't result in a usable page for me.
Comment 3 François Lamboley 2017-01-31 14:37:48 PST
Created attachment 300263 [details]
Same example as previous, without the JS (HTML)

Apologies, previous attachment had to be opened with JS disabled. I modified the page slightly to remove all JS.
Comment 4 Simon Fraser (smfr) 2017-01-31 14:43:23 PST
That content fails to load all its CSS files.
Comment 5 François Lamboley 2017-01-31 14:50:19 PST
Sorry again. It worked in Safari, not in Technology preview because it tried loading local resources, which is disallowed in TP.

To avoid further troubles, I hosted the test page here:
https://frostland.fr/slow_scroll/
Comment 6 Simon Fraser (smfr) 2017-02-03 18:52:49 PST
The page is using a scrollable <div> rather than page scrolling with a fixed bar.