Bug 180489

Summary: Page with Many Tables Takes About 4 Seconds to Display
Product: WebKit Reporter: Neil Daniels <neil.here>
Component: Layout and RenderingAssignee: Nobody <webkit-unassigned>
Status: NEW    
Severity: Normal CC: bfulgham, simon.fraser, webkit-bug-importer, zalan
Priority: P2 Keywords: InRadar
Version: Safari Technology Preview   
Hardware: Unspecified   
OS: Unspecified   
Attachments:
Description Flags
Webarchive of page with slow performance
none
Video of slow performance w/ Web Inspector visible none

Neil Daniels
Reported 2017-12-06 10:59:54 PST
Created attachment 328591 [details] Webarchive of page with slow performance A webpage with many tables takes about 4 seconds to render on my computer. The latest versions of Firefox and Chrome can both display the page within half a second. The rendering/display process is slow enough that the Web Inspector stops showing process before the page is even displayed. The issue does not seem to be (entirely?) style dependent; removing/excluding the CSS file has similar load times. An example URL of a page that has slow performance is: https://www.fomopop.com/guides/live-tv-streaming/channels (this is also attached as a webarchive). I'm testing on Safari Technology Preview Release 45 (Safari 11.1, WebKit 13605.1.15.2). My machine is a MacBook Pro (15-inch, Late 2016) running 10.13.1 (17B1003).
Attachments
Webarchive of page with slow performance (310.23 KB, application/x-webarchive)
2017-12-06 10:59 PST, Neil Daniels 		no flags
Details
Video of slow performance w/ Web Inspector visible (7.00 MB, video/quicktime)
2017-12-06 11:00 PST, Neil Daniels 		no flags
Details
View All Add attachment proposed patch, testcase, etc.
Neil Daniels
Comment 1 2017-12-06 11:00:47 PST
Created attachment 328594 [details] Video of slow performance w/ Web Inspector visible
Radar WebKit Bug Importer
Comment 2 2017-12-06 11:22:48 PST
<rdar://problem/35886705>
Simon Fraser (smfr)
Comment 3 2017-12-06 11:23:21 PST
The JS in the page is triggering a lot of forced layouts via calls to clientWidth().
Neil Daniels
Comment 4 2017-12-07 11:18:19 PST
(In reply to Simon Fraser (smfr) from comment #3) > The JS in the page is triggering a lot of forced layouts via calls to > clientWidth(). I still get slow performance with JavaScript disabled at the browser-level.
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