GIMP lags while Xorg uses much CPU

[Helco]

GIMP lags to the point of not being of any use, when either the windowed Single-Window-Mode is being used or the Non-Single-Window-Mode has an image loaded (the lag occurs only in the main window)
Selecting a menu bar item works fine, also the tooltips for the drawing tools pop up on time, but the main window content needs up to several seconds to react to clicks and even hovering over a drawing tool (in the Single-Window-Mode).
No rulers were visible, I do not use a tablet and the resizing the window did not reduce the lag.

This bug affected the 2.8.14 version supplied via the ubuntu repositories, also my current 2.8.16 version, which was supplied via ppa:otto-kesselgulasch/gimp

I ran top while moving the mouse over the window:
 - "Xorg" uses between 15% and 25%
 - "Compiz" uses between 5% and 10%
 - "gimp-2.8" uses at most 5%

"dpkg-query -W xorg" returned "xorg 1:7.7+7ubuntu4"

With compizconfig-settings-manager I disabled all effects, which did not fix the problem

I seem to be also affected by https://bugs.launchpad.net/ubuntu/+source/compiz/+bug/1072206, but only if the Non-Single-Window-Mode is being used.

My System:
OS: Ubuntu 15.10 (Kernel 4.2.0-23-generic x86_64)
CPU: Intel(R) Core(TM) i7-3610QM CPU @ 2.30GHz
GPU: Nvidia Geforce GT 630M (using the Nvidia driver 361.28)

I originally filed a bug to the GIMP bugtracker (https://bugzilla.gnome.org/show_bug.cgi?id=763138), but I was encouraged to file a bug here instead.

ProblemType: Bug
DistroRelease: Ubuntu 15.10
Package: xorg 1:7.7+7ubuntu4
ProcVersionSignature: Ubuntu 4.2.0-23.28-generic 4.2.6
Uname: Linux 4.2.0-23-generic x86_64
NonfreeKernelModules: nvidia_uvm nvidia_modeset nvidia
.proc.driver.nvidia.registry: Binary: ""
.proc.driver.nvidia.version:
 NVRM version: NVIDIA UNIX x86_64 Kernel Module 361.28 Wed Feb 3 15:48:04 PST 2016
 GCC version: gcc version 5.2.1 20151010 (Ubuntu 5.2.1-22ubuntu2)
ApportVersion: 2.19.1-0ubuntu5
Architecture: amd64
CurrentDesktop: Unity
Date: Sat Mar 5 19:15:11 2016
DistUpgraded: Fresh install
DistroCodename: wily
DistroVariant: ubuntu
DkmsStatus:
 bbswitch, 0.7, 4.2.0-16-generic, x86_64: installed
 bbswitch, 0.7, 4.2.0-23-generic, x86_64: installed
 nvidia-361, 361.28, 4.2.0-23-generic, x86_64: installed
GraphicsCard:
 Intel Corporation 3rd Gen Core processor Graphics Controller [8086:0166] (rev 09) (prog-if 00 [VGA controller])
   Subsystem: ASUSTeK Computer Inc. Device [1043:10bc]
 NVIDIA Corporation GF108M [GeForce GT 630M] [10de:0de9] (rev a1) (prog-if 00 [VGA controller])
   Subsystem: ASUSTeK Computer Inc. Device [1043:10bc]
InstallationDate: Installed on 2016-01-15 (50 days ago)
InstallationMedia: Ubuntu 15.10 "Wily Werewolf" - Release amd64 (20151021)
MachineType: ASUSTeK COMPUTER INC. K75VM
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.2.0-23-generic root=UUID=47915adc-f8da-436b-8c87-3e2a1e6c76d8 ro quiet splash
SourcePackage: xorg
Symptom: display
UdevLog: Error: [Errno 2] Datei oder Verzeichnis nicht gefunden: '/var/log/udev'
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 11/25/2014
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: 234
dmi.board.asset.tag: To be filled by O.E.M.
dmi.board.name: K75VM
dmi.board.vendor: ASUSTeK COMPUTER INC.
dmi.board.version: 1.0
dmi.chassis.asset.tag: No Asset Tag
dmi.chassis.type: 10
dmi.chassis.vendor: ASUSTeK COMPUTER INC.
dmi.chassis.version: 1.0
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr234:bd11/25/2014:svnASUSTeKCOMPUTERINC.:pnK75VM:pvr1.0:rvnASUSTeKCOMPUTERINC.:rnK75VM:rvr1.0:cvnASUSTeKCOMPUTERINC.:ct10:cvr1.0:
dmi.product.name: K75VM
dmi.product.version: 1.0
dmi.sys.vendor: ASUSTeK COMPUTER INC.
version.compiz: compiz 1:0.9.12.2+15.10.20151202-0ubuntu1
version.ia32-libs: ia32-libs N/A
version.libdrm2: libdrm2 2.4.64-1
version.libgl1-mesa-dri: libgl1-mesa-dri 11.0.2-1ubuntu4
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 11.0.2-1ubuntu4
version.nvidia-graphics-drivers: nvidia-graphics-drivers-* N/A
version.xserver-xorg-core: xserver-xorg-core 2:1.17.2-1ubuntu9.1
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.9.2-1ubuntu1
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:7.5.0+git20150819-0ubuntu1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917+git20150808-0ubuntu4
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.11-1ubuntu3
xserver.bootTime: Fri Feb 26 13:52:26 2016
xserver.configfile: /etc/X11/xorg.conf
xserver.errors:

xserver.logfile: /var/log/Xorg.0.log
xserver.version: 2:1.17.2-1ubuntu9.1

[penalvch (penalvch)]

Helco, thank you for reporting this and helping make Ubuntu better.

To see if this is already resolved, could you please test http://cdimage.ubuntu.com/daily-live/current/ and advise to the results?

[Launchpad Janitor (janitor)]

[Expired for xorg (Ubuntu) because there has been no activity for 60 days.]