gnome-shell uses high CPU when simply moving windows

[Fredrik Öhrström]

After doing a stock install Ubuntu 18.04.1 LTS on an imac 27" 2010
8G ram, Intel® Core™ i7 CPU 870 @ 2.93GHz × 8

Simply moving a window around on the screen increases the cpu usage
by gnome-shell to 44%. When displaying a movie, totem takes 10%, gnome-shell takes 22%.
etc etc

System: Host: oldie Kernel: 4.15.0-36-generic x86_64 bits: 64 Desktop: Gnome 3.28.3
           Distro: Ubuntu 18.04.1 LTS
Machine: Device: desktop System: Apple product: iMac11 3 v: 1.0 serial: N/A
           Mobo: Apple model: Mac-F2238BAE v: iMac11 3 serial: N/A
           UEFI: Apple v: IM112.88Z.0057.B01.1112090906 date: 12/09/11
CPU: Quad core Intel Core i7 870 (-MT-MCP-) cache: 8192 KB
           clock speeds: max: 2927 MHz 1: 1271 MHz 2: 1206 MHz 3: 1374 MHz 4: 1271 MHz 5: 1377 MHz 6: 1266 MHz
           7: 1693 MHz 8: 1279 MHz
Graphics: Card: Advanced Micro Devices [AMD/ATI] Broadway PRO [Mobility Radeon HD 5850]
           Display Server: x11 (X.Org 1.19.6 ) driver: radeon Resolution: 2560x1440@59.95hz
           OpenGL: renderer: AMD JUNIPER (DRM 2.50.0 / 4.15.0-36-generic, LLVM 6.0.0) version: 3.3 Mesa 18.0.5
Audio: Card-1 Intel 5 Series/3400 Series High Definition Audio driver: snd_hda_intel
           Card-2 Advanced Micro Devices [AMD/ATI] Juniper HDMI Audio [Radeon HD 5700 Series]
           driver: snd_hda_intel
           Sound: Advanced Linux Sound Architecture v: k4.15.0-36-generic
Network: Card-1: Broadcom Limited NetXtreme BCM5764M Gigabit Ethernet PCIe driver: tg3
           IF: enp2s0 state: up speed: 1000 Mbps duplex: full mac: c4:2c:03:30:ce:8e
           Card-2: Qualcomm Atheros AR928X Wireless Network Adapter (PCI-Express) driver: ath9k
           IF: wls1 state: down mac: d8:30:62:67:2a:19
Drives: HDD Total Size: 2500.5GB (38.0% used)
           ID-1: /dev/sda model: WDC_WD1001FALS size: 1000.2GB
           ID-2: USB /dev/sdb model: MK1059GSM size: 1000.2GB
           ID-3: USB /dev/sdd model: Elements_10B8 size: 500.1GB
Partition: ID-1: / size: 226G used: 125G (58%) fs: ext4 dev: /dev/sda2
           ID-2: /home size: 701G used: 876M (1%) fs: btrfs dev: /dev/sda4
RAID: No RAID devices: /proc/mdstat, md_mod kernel module present
Sensors: System Temperatures: cpu: 56.0C mobo: N/A
           Fan Speeds (in rpm): cpu: 936
Info: Processes: 342 Uptime: 3:07 Memory: 2087.3/7967.4MB Client: Shell (bash) inxi: 2.3.56

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: gnome-shell 3.28.3-0ubuntu0.18.04.2
ProcVersionSignature: Ubuntu 4.15.0-36.39-generic 4.15.18
Uname: Linux 4.15.0-36-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.4
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Mon Oct 22 19:09:59 2018
DisplayManager: gdm3
GsettingsChanges:
 b'org.gnome.shell' b'disable-user-extensions' b'true'
 b'org.gnome.shell' b'app-picker-view' b'uint32 1'
 b'org.gnome.shell' b'favorite-apps' redacted by apport
 b'org.gnome.desktop.interface' b'gtk-im-module' b"'gtk-im-context-simple'"
InstallationDate: Installed on 2018-10-22 (0 days ago)
InstallationMedia: Ubuntu 18.04.1 LTS "Bionic Beaver" - Release amd64 (20180725)
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=sv_SE.UTF-8
 SHELL=/bin/bash
SourcePackage: gnome-shell
UpgradeStatus: No upgrade log present (probably fresh install)

[Daniel van Vugt (vanvugt)]

Thanks for the bug report.

I happen to be working on fixes for this right now, and had not yet created a bug for it. So let's use this bug.

The relevant fixes I have so far are:
https://gitlab.gnome.org/GNOME/mutter/merge_requests/189
https://gitlab.gnome.org/GNOME/gjs/merge_requests/236
https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/265
https://gitlab.gnome.org/GNOME/mutter/merge_requests/270

[Launchpad Janitor (janitor)]

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

[Fredrik Öhrström (oehrstroem)]

Thank you! After reading through the reference bugs, it seems like you have a bit of a handful here.

I have temporarily switch back to unity since the stuttering of movies and general slugginesh due to gnome-shell is not bearable. But let me know if you need testing and I will switch back and test any solutions you have created.

[Daniel van Vugt (vanvugt)]

The GJS fix is now in 19.04 here:
https://launchpad.net/ubuntu/+source/gjs/1.54.2-1

[Daniel van Vugt (vanvugt)]

The gjs tasks are effectively tracked via bug 1803271.

[Daniel van Vugt (vanvugt)]

I think it's too early for this to be a release bug. A bunch of fixes are still awaiting upstream review, some require more upstream work by me, and the final one needs to be rewritten completely after so re-profiling. Lots of upstream work to do before considering this for distro.

[Daniel van Vugt (vanvugt)]

Now tracking the required fixes here:
https://gitlab.gnome.org/GNOME/mutter/issues/590