SUMMARY When Night Light is active the desktops responsiveness is very bad. It's pretty much unusable, I get noticeable lag between pressing keys on my keyboard and them showing up in konsole. No such issue when using X11 session. I'm using an old Dell laptop with an Intel GPU STEPS TO REPRODUCE 1. Login to Plasma Wayland session 2. enalbe Night Light (wait till it's active) OBSERVED RESULT Desktop becomes slow. Typing is slow, interacting with K menu is slow. Night Light itself works as I can see the screen colour changing to more warm/red. After deactivating Night Light it returns to normal after a few seconds. I think the colour shift is gradual. EXPECTED RESULT Desktop works as fast as before Night Light was activated. As fast as X11 session which doesn't have this slowdown when using Night Light. SOFTWARE/OS VERSIONS Operating System: Fedora Linux 43 KDE Plasma Version: 6.5.4 KDE Frameworks Version: 6.21.0 Qt Version: 6.10.1 Kernel Version: 6.17.12-300.fc43.x86_64 (64-bit) Graphics Platform: Wayland Processors: 2 × Intel® Core™2 Duo CPU T7250 @ 2.00GHz Memory: 4 GiB of RAM (3.8 GiB usable) Graphics Processor: llvmpipe Manufacturer: Dell Inc. Product Name: Latitude D630 ADDITIONAL INFORMATION lspci output regarding my GPU: 00:02.0 VGA compatible controller: Intel Corporation Mobile GM965/GL960 Integrated Graphics Controller (primary) (rev 0c) This has become a problem since Fedora upgraded to Plasma 6.3 (not 100% sure, might've been 6.2). Before Plasma Wayland didn't have this issue when using Night Light. I've never experienced this issue on Plasma X11 session.
> Graphics Processor: llvmpipe You don't have working hardware acceleration, likely because the GPU is just too old to run shaders with more than a few instructions. Color management features like night light require a bit more complex shader, and that affects llvmpipe performance badly. It's only faster on X11 and older versions of Plasma because night light isn't fully implemented there. With a core duo, even slightly complex shaders in llvmpipe being very slow isn't really unexpected. To be honest, I'm surprised it's even usable without night light.
(In reply to Zamundaaa from comment #1) > > Graphics Processor: llvmpipe > You don't have working hardware acceleration, likely because the GPU is just > too old to run shaders with more than a few instructions. > > Color management features like night light require a bit more complex > shader, and that affects llvmpipe performance badly. It's only faster on X11 > and older versions of Plasma because night light isn't fully implemented > there. > > With a core duo, even slightly complex shaders in llvmpipe being very slow > isn't really unexpected. To be honest, I'm surprised it's even usable > without night light. That's disappointing and surprising. It used to work fine on Wayland before 6.2 (or 6.3, I can't remember when exactly this started). And there are no such issues when I use X11 session. Night light engages and there's no slow down. So the hardware can manage it. It seems like the implementation changed at some point and is highly inefficient.
It really only has a few more instructions in the shader vs. the normal one. It doesn't seem surprising to me that a 19 year old laptop CPU struggles with that though. Like I said already, it's astonishing it's even fast enough for direct copying with the simpler shaders.