Xorg high CPU usage and stuttering on ubuntu 20.04

[Harrison]

Hi there!

I'm experiencing some stuttering on my machine after running updates today Mar 18th. The stuttering is for all visual effects including mouse movement, videos playing, dragging windows, animations and more. The stuttering is not affecting sound (as far as I can tell). The stuttering does not seem to happen on any regular interval, but does happen every 500-1000ms lasting for 50-100ms... just enough to be annoying enough to open a bug report :P

I think that this issue is related to Xorg and the nvidia drivers doing something, but I'm not sure what exactly could be the issue.

Here are some related links that led me to report this bug:
- https://unix.stackexchange.com/questions/568173/nvidia-drivers-390-440-stuttering-ubuntu-20-04
  - This led me to start thinking that the problem could be with Xorg or nvidia
- https://bugs.launchpad.net/ubuntu/+source/nvidia-graphics-drivers-440/+bug/1867352
  - I'm experiencing all of these problems reported (including the Xorg.conf message), but I'm not getting a full freeze, I'm only getting stuttering)

Steps I've taken:
- Updated my system to latest packages on 20.04
- Installed [kwin-lowlatency](https://github.com/tildearrow/kwin-lowlatency) when I thought it might be related to the compositor
- Toggled various compositor and Xorg settings
- A few reboots here and there

If I'm not including enough information please let me know what else to include and how to report it.

Thanks!
--Harrison

System Information:

```
% sudo lsb_release -rd
Description: Ubuntu Focal Fossa (development branch)
Release: 20.04
```

```
% sudo apt-cache policy nvidia-driver-440
nvidia-driver-440:
  Installed: 440.64-0ubuntu2
  Candidate: 440.64-0ubuntu2
  Version table:
 *** 440.64-0ubuntu2 500
        500 http://us.archive.ubuntu.com/ubuntu focal/restricted amd64 Packages
        100 /var/lib/dpkg/status
     440.64-0ubuntu0~0.20.04.2 500
        500 http://ppa.launchpad.net/graphics-drivers/ppa/ubuntu focal/main amd64 Packages
```

```
% ubuntu-drivers devices
== /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0 ==
modalias : pci:v000010DEd00001B06sv00003842sd00006393bc03sc00i00
vendor : NVIDIA Corporation
model : GP102 [GeForce GTX 1080 Ti]
driver : nvidia-driver-440 - distro non-free recommended
driver : nvidia-driver-390 - distro non-free
driver : nvidia-driver-435 - distro non-free
driver : xserver-xorg-video-nouveau - distro free builtin
```

[Harrison (hjkatz03)]

Closed in favor of https://bugs.launchpad.net/ubuntu/+source/xorg/+bug/1868009

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.