My system info is at the bottom of this post. I'm experiencing insane levels of screen flickering on the latest Neon User Edition. It's to the point where it hurts to look at the screen! It happens pretty much whenever I open any program at all. You can see a video of the problem at https://www.youtube.com/watch?v=jiUl26o0hcQ. I've tried the following combinations of settings, and nothing helps:

Scale Method Accurate + Rendering backend OpenGL 3.1 + Tearing Prevention Automatic
Scale Method Accurate + Rendering backend OpenGL 3.1 + Tearing Prevention Never
Scale Method Accurate + Rendering backend OpenGL 3.1 + Tearing Prevention Full Screen Repaints
Scale Method Accurate + Rendering backend OpenGL 3.1 + Tearing Prevention Re-use screen content
Scale Method Accurate + Rendering backend OpenGL 3.1 + Tearing Prevention Only when cheap

Scale Method Accurate + Rendering backend OpenGL 2.0 + Tearing Prevention Automatic
Scale Method Accurate + Rendering backend OpenGL 2.0 + Tearing Prevention Never
Scale Method Accurate + Rendering backend OpenGL 2.0 + Tearing Prevention Full Screen Repaints
Scale Method Accurate + Rendering backend OpenGL 2.0 + Tearing Prevention Re-use screen content
Scale Method Accurate + Rendering backend OpenGL 2.0 + Tearing Prevention Only when cheap

The results are uniformly awful. The only thing that produces any improvement is the XRender option, but that has really bad performance.

There are tons of reports of issues like this out there, for various versions of KDE/Plasma, going back many years, and most suggestions just haven't worked for me.

Can anyone lend a hand?

Thanks!

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System:    Host: MyBox Kernel: 4.12.4-041204-generic x86_64 (64 bit gcc: 6.3.0)
           Desktop: KDE Plasma 5.10.4 (Qt 5.9.1) dm: sddm,sddm Distro: Ubuntu 16.04 xenial
Machine:   System: LENOVO (portable) product: 000000 v: ThinkPad Chassis: type: 10
           Mobo: LENOVO model: 000000 v: 00000 WIN Bios: LENOVO v: N1DET87W (2.15 ) date: 05/17/2017
CPU:       Quad core Intel Core i7-6700HQ (-HT-MCP-) cache: 6144 KB
           flags: (lm nx sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx) bmips: 20736
           clock speeds: min/max: 800/3500 MHz 1: 799 MHz 2: 799 MHz 3: 799 MHz 4: 984 MHz 5: 924 MHz 6: 799 MHz
           7: 799 MHz 8: 799 MHz
Graphics:  Card: NVIDIA GM107GLM [Quadro M600M] bus-ID: 01:00.0 chip-ID: 10de:13b2
           Display Server: X.Org 1.18.4 drivers: nvidia (unloaded: fbdev,vesa,nouveau)
           Resolution: 1920x1080@60.00hz, 1920x1080@60.00hz
           GLX Renderer: Quadro M600M/PCIe/SSE2 GLX Version: 4.5.0 NVIDIA 384.59 Direct Rendering: Yes
Audio:     Card-1 NVIDIA Device 0fbc driver: snd_hda_intel bus-ID: 01:00.1 chip-ID: 10de:0fbc
           Card-2 Intel Sunrise Point-H HD Audio driver: snd_hda_intel bus-ID: 00:1f.3 chip-ID: 8086:a170
           Sound: Advanced Linux Sound Architecture v: k4.12.4-041204-generic
Network:   Card-1: Intel Ethernet Connection (2) I219-V
           driver: e1000e v: 3.2.6-k bus-ID: 00:1f.6 chip-ID: 8086:15b8
           IF: enp0s31f6 state: up speed: 1000 Mbps duplex: full mac: <filter>
           Card-2: Intel Wireless 8260 bus-ID: 04:00.0 chip-ID: 8086:24f3
           IF: N/A state: N/A mac: N/A
Sensors:   System Temperatures: cpu: 71.0C mobo: N/A gpu: 0.0:59C
           Fan Speeds (in rpm): cpu: 0
Info:      Processes: 376 Uptime: 10:42 Memory: 7857.8/32066.7MB Init: systemd v: 229 runlevel: 5 Gcc sys: 5.4.0
           Client: Shell (bash 4.3.481 running in konsole) inxi: 2.2.35


Somewhere in System Settings,

there's a setting to highlight screen areas
being updated/redrawn
(for debugging/testing).

Switch it OFF (if it's activated).

Goto "Workspace": "Desktop Behavior"
It's under "Desktop Effects":

==> "Show Paint"

NoNameNoBlame wrote:Somewhere in System Settings,

there's a setting to highlight screen areas
being updated/redrawn
(for debugging/testing).

Switch it OFF (if it's activated).

It already was off. Just out of curiosity, I turned it on for a second right now, and the effect is very distinctive when its on -- different parts of the screen are coloured red, green, blue, etc. None of that's the case in the screen grab video.

After having clarified this,

Try (if You have not already):

"Hardware" "Display and Monitor":
Under "Compositor":

==> Rendering Backend: OpenGL
==> vsync: Full Screen Repaints

And play around with the other settings there, maybe.

I forgot telling You to
logOFF/logON
after changing the settings.

To test Your Settings and isolate problems:

Open Terminal
Start glxgears

Wait and look at frame rates printed:

Should be near 60 FramesPerSecond
for Standard LCD-Monitor.

If this doesn't lead to solution:

Install twm or cwm.
Login into this, and not into KDE Plasma.

Repeat 'glxgears'-test there.

If it's as bad as under KDE Plasma,
then You don't have a KDE problem, at all.

Then You have to look at Your distribution's
(Ubuntu's/Debian's/SuSE's, …)
'X Window System'-Forum.

To get the FramesPerSecond
of the 'X Window System'
underlying _A_N_Y_ desktop environment (e.g. KDE Plasma),

in a terminal window (e.g. konsole),

You can _A_L_W_A_Y_S_ do:


# 2 SPACEs: ==> <"> <SPACE> <SPACE> <"> <==

$ xrandr | grep " "
1920x1200 60.24*+

Meaning: 60.24 Hz (FramesPerSecond)
for the 'X Window System'.

That's the Maximum 'KDE Plasma' can get.

Thanks very much for your help! I seem to have solved the problem, at least for now. What I did:

• Selected OpenGL 3.1 as Rendering backend.
• Chose Full Screen Repaints for Tearing prevention
• Added a script containing

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  export KWIN_TRIPLE_BUFFER=1

  to

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  /etc/profile.d/

Also, I rebooted. I hadn't done this in all my systematic testing of various settings before, and thus nothing worked (even though things would change to some degree).

I should note that with OpenGL, the BreezeDark theme's panels have no transparency -- only Xrender does this properly for whatever reason. But this is something I can live with.