Nextcloud 15 slow frontend with Chrome 72

Nextcloud version: 15.0.5
Operating system and version: Gentoo x64
nginx version : 1.15.9
PHP version: 7.1.28


Shortly after upgrading Nextcloud to version 15.0.5, I started experiencing very unresponsive behavior, e.g. every action on the web frontend takes 2-3 seconds to complete, which wasn’t the case before.

I started from the backend, but there are no signs of high resource use from Nginx, Maria or Redis on the server.

On my desktop however, every time I move to the tab in Chrome which has Nextcloud opened, the CPU and MEM jump from 1-3% to 40% for 2-3 seconds, and then spike every time I do something in Nextcloud (and also in Rainloop, which I run as an app)

There are no errors in the Admin/Logging section with a recent date.
The same is observed in Chrome Incognito mode.
I cannot reproduce this behavior with any other webpage.

Is anyone aware of such problems and knows a solution?

You upgraded, so you were using NC 14 before?

Do you use theming? Other browsers show the same problem? All apps are updated?

Yes, I might miss a minor version, but never a major. I migrated from Owncloud around v 12 or 13.

I don’t use theming. Everything is marked as up to date in the list of apps.

I just pulled the bin of Firefox-66 and it didn’t have excessive latency (not saying it couldn’t be more responsive). Clicking around a lot couldn’t consume more than 4.5% CPU however.

Update: having the same problem with Chrome 73. Any advice how to test/debug this to give better clues?