NEW 191637
Scrolling is choppy on exocomics.com in Safari but not in Chrome 
https://bugs.webkit.org/show_bug.cgi?id=191637
Summary Scrolling is choppy on exocomics.com in Safari but not in Chrome
Zev Eisenberg
Reported 2018-11-14 09:29:41 PST
Created attachment 354820 [details] video demonstrating the issue in Safari On pages on exocomics.com, such as https://www.exocomics.com/540, page scrolling is quite choppy on my MacBook Pro 15-inch 2018 running Safari 12.0.1 (14606.2.104.1.1) on macOS 10.14.1 (18B75). It's also choppy on Safari Technology Preview Release 69 (Safari 12.1, WebKit 14607.1.12). But scrolling is buttery smooth on Chrome Version 70.0.3538.102 (Official Build) (64-bit). Please let me know if I should file a radar instead.
Attachments
video demonstrating the issue in Safari (49.66 MB, video/quicktime)
2018-11-14 09:29 PST, Zev Eisenberg 		no flags
Details
sample of the Safari Web Content process reproducing the bug (590.71 KB, text/plain)
2018-11-14 09:40 PST, Zev Eisenberg 		no flags
Details
View All Add attachment proposed patch, testcase, etc.
Zev Eisenberg
Comment 1 2018-11-14 09:40:22 PST
Created attachment 354822 [details] sample of the Safari Web Content process reproducing the bug Adding attached sample of Safari Web Content during bug reproduction
Simon Fraser (smfr)
Comment 2 2018-11-14 11:55:33 PST
The page has background-attachment:fixed: on both body and html, and different background images on each, so we fall out of our optimized scrolling code path.
Zev Eisenberg
Comment 3 2019-06-17 17:14:56 PDT
Just re-tested in Safari 12.1.1 (14607.2.6.1.1) on macOS 10.14.5 (18F203), and scrolling is smooth now. The web page appears not to have changed, so it looks like this is fixed in Safari now. Going to leave open because I’m not sure what to do, but feel free to mark as resolved if appropriate.
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