Performance issue in large list in Chrome browser

Steps to reproduce

Just browse
Propædia - Dynalist (it is the demo document)
dynalist-2019-9-6 - Dynalist (the clone i made in my folder)
in Chrome

Expected result

Smooth scrolling and no lagging

Actual result

CPU usage is high and scrolling is lagging.
When I use the Dev Tool to do performance profiling, it shows that some tasks are running even though the window is just idling.


desktop version/ Google Chrome 76.0 / Windows 10

Additional information

This issue is not found in Firefox.

So one of the optimizations in Dynalist is that not all items are “rendered” when you load a document - anything that’s out of view is initialized as a grey box and to be filled in later.

We have a background task to fill them in gradually, but I think there’s a few things we could be doing better to avoid the reflow it seems to be causing right now.

Perhaps Firefox deals with those reflows better? I’m not sure. But it’s definitely something we can fix. Stay tuned!