Bug 167561 - Sluggish/slow scroll on some webpages
Summary: Sluggish/slow scroll on some webpages
Status: NEW
Alias: None
Product: WebKit
Classification: Unclassified
Component: Layout and Rendering (show other bugs)
Version: Safari Technology Preview
Hardware: Macintosh macOS 10.12
: P2 Normal
Assignee: Nobody
Keywords: InRadar
Depends on:
Reported: 2017-01-29 07:40 PST by François Lamboley
Modified: 2017-02-03 18:52 PST (History)
5 users (show)

See Also:

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

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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
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:
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.