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.
I've joined the WebPage in two formats (Safari WebArchive & pure HTML).
I can join another example of a WebPage with this sluggish scroll if needed.
The attached webarchive and HTML didn't result in a usable page for me.
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.
That content fails to load all its CSS files.
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:
The page is using a scrollable <div> rather than page scrolling with a fixed bar.