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  • Chrome Version: Google Chrome 70.0.3538.77 (Official Build) (64-bit)
  • OS: Ubuntu

Try opening one of these pages:

Scrolling is very laggy. I hit up the profiler and it shows me this:

enter image description here

This shows that scrolling triggers a lot of reflows. Further investigation suggests that this is coming from Popper.js somehow (bit hard to tell from the minified source though).

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    I have observed it on meta too, long/more answers sometimes create blank pages – ankii Sep 7 at 20:15
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    I can reproduce frametimes around 80-95 ms on your first link with Chrome on Windows 10. The forced reflows certainly look unusual. – Mad Scientist Sep 7 at 22:28
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    I confirm, scrolling through those pages is very laggy. Similar behaviour on google chrome 76.0.3809.132 (Official Build) (64-bit). meta.stackoverflow.com/questions/389212 – notyourdolly Sep 8 at 14:25
  • Can you try a different browser? I see no lagginess in Firefox 69.0 (logged in to SO) or in Edge (not logged in) on Windows 10. – Andrew Morton Sep 8 at 16:04
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    @Andrew Morton: Guessing it's a Chromium issue then. Blink!Edge reproduces this issue; EdgeHTML!Edge doesn't. – BoltClock's a Unicorn Sep 8 at 17:29
  • @AndrewMorton Indeed, Firefox 69.0 (64-bit) works fine for me too on Ubuntu. – Attila Kun Sep 8 at 18:35
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  • This seems to be fixed now, at least I can't reproduce it anymore. – Attila Kun Sep 15 at 0:49
  • Yeah, fix was in at the tail end of last week; updated – Shog9 Sep 17 at 19:56
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Thanks for the report! The root cause here was a script library we use to handle pop-ups combined with the presence of an invisible pop-up for every answer on the page.

Should now be fixed. Details: Scrolling performance in Chrome in large posts suddenly got worse over the past week

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