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

François Lamboley
Reported 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.
Attachments
An example of a WebSite with a sluggish scroll (WebArchive and HTML) (2.29 MB, application/zip)
2017-01-29 07:40 PST, François Lamboley 		no flags
Details
Same example as previous, without the JS (HTML) (1.15 MB, application/zip)
2017-01-31 14:37 PST, François Lamboley 		no flags
Details
Show Obsolete (1) View All Add attachment proposed patch, testcase, etc.
Radar WebKit Bug Importer
Comment 1 2017-01-29 16:21:49 PST
<rdar://problem/30255300>
Simon Fraser (smfr)
Comment 2 2017-01-30 10:32:17 PST
The attached webarchive and HTML didn't result in a usable page for me.
François Lamboley
Comment 3 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.
Simon Fraser (smfr)
Comment 4 2017-01-31 14:43:23 PST
That content fails to load all its CSS files.
François Lamboley
Comment 5 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/
Simon Fraser (smfr)
Comment 6 2017-02-03 18:52:49 PST
The page is using a scrollable <div> rather than page scrolling with a fixed bar.
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