gnome-shell is taking more and more CPU over time, UI becomes slowly unusable

I'm a relatively heavy desktop user, having multiple browsers running at any given time, lots of terminal windows, etc. However, my browsers don't use a lot of CPU as most of the tabs are suspended at any given moment.

On a regular basis, over time, my desktop becomes less and less usable. It starts with becoming noticeably slower, laggy, and eventually absolutely requiring a reboot since it becomes totally unusable.

At the same time my my system load is low, and remains low, while gnome-shell appears only to take more and more CPU. I often see it using 30, 50, 90, and sometimes 100% CPU, while the rest is idle.

It reaches the point where terminals don't easily

The only "fix" is rebooting, or restarting X.

I must admit that I've been seeing this on my laptop for years now, and there is no improvement in sight even though I upgrade Ubuntu to the next version every time an update is out.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: gnome-shell 3.36.2-1ubuntu1~20.04.1
ProcVersionSignature: Ubuntu 5.4.0-33.37-generic 5.4.34
Uname: Linux 5.4.0-33-generic x86_64
ApportVersion: 2.20.11-0ubuntu27.3
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: ubuntu:GNOME
Date: Thu Jun 18 11:53:00 2020
DisplayManager: gdm3
RelatedPackageVersions: mutter-common 3.36.2-1ubuntu1~20.04.1
SourcePackage: gnome-shell
UpgradeStatus: Upgraded to focal on 2020-04-28 (50 days ago)