low performance when using Zoom client compared to linux-generic 5.4.0.x

[Laurent CREPET]

Hi,

Recently, I got kernel linux-generic-hwe-20.04 installed, so 5.11.0.x. Not sure if I intended to, as I already tested when it was based on 5.8.x, but got the same issue... So, well, as many, I use Zoom client (latest deb file downloaded from Zoom site) on the following laptop:

Manufacturer: Dell Inc.
Product Name: Latitude 7400
CPU: Intel(R) Core(TM) i7-8665U CPU @ 1.90GHz

With linux-generic-hwe-20.04 based on 5.8.x, I noticed a huge increase of CPU used by Zoom (just looking at top), sometimes having 350% when someones was sharing screen.

With linux-generic-hwe-20.04 based on 5.11. the CPU usage seems correct, but the load average get doubled after a moment, and the system becomes far less usable.

Going back to linux-kernel 5.4.0-84-generic, and performance is stable, even without thinking about
changing the CPU governor to performance.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: linux-generic-hwe-20.04 5.11.0.34.36~20.04.13
ProcVersionSignature: Ubuntu 5.4.0-84.94-generic 5.4.133
Uname: Linux 5.4.0-84-generic x86_64
ApportVersion: 2.20.11-0ubuntu27.18
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: ubuntu:GNOME
Date: Thu Sep 9 15:28:58 2021
InstallationDate: Installed on 2021-02-09 (211 days ago)
InstallationMedia: Ubuntu 20.04.2 LTS "Focal Fossa" - Release amd64 (20210204)
SourcePackage: linux-meta-hwe-5.11
UpgradeStatus: No upgrade log present (probably fresh install)