Bug 430143

Thanks for the report! It's not reproducible in 25.07.70 and I can see no recent similar reports about this, so there's a strong chance this is fixed by now. If you’re still experiencing it, let us know — we’re happy to reopen it!

(In reply to Lenzoid from comment #1)
> Thanks for the report! It's not reproducible in 25.07.70 and I can see no
> recent similar reports about this, so there's a strong chance this is fixed
> by now. If you’re still experiencing it, let us know — we’re happy to reopen
> it!

Hi! Could you please confirm if it's not reproducible using the 30mb sample mentioned in Bug 504267. The window must be maximised, and the zoom percentage should be set to 35%.

It's much more noticeable at 2560x1440 compared to 1920x1080. For some reason the other zoom percentages have less lag, 100% and 25% are much smoother than 35% zoom. Restoring the window to a smaller size also makes it smoother.

I can reproduce it in KDE Neon Unstable, but it ships with an older version of Gwenview (25.04.1).

KDE Neon Unstable (neon-unstable-20250608-1147)
KDE Plasma Version: 6.4.80
KDE Frameworks Version: 6.15.0
QT Version: 6.9.0
Kernel: 6.11.0

Yes I tried with Gwenview 25.04.2 (from Flatpak) and 25.04.2 from 6.4 Beta. I could not exactly reproduce 35% zoom but 36%. Transition from picture to picture is smooth, also to and from the huge pictures.

Operating System: Arch Linux 
KDE Plasma Version: 6.3.91
KDE Frameworks Version: 6.14.0
Qt Version: 6.9.1
Kernel Version: 6.14.10-arch1-1 (64-bit)
Graphics Platform: Wayland
Processors: 16 × AMD Ryzen 7 5700X3D 8-Core Processor
Memory: 32 GiB of RAM (31.3 GiB usable)
Graphics Processor: NVIDIA GeForce RTX 2070 SUPER 
Manufacturer: Micro-Star International Co., Ltd.
Product Name: MS-7B85
System Version: 1.0
nvidia-open-dkms 575.57.08-1

I can also reproduce this on my Intel laptop, so it's not just exclusive to my AMD PC. On the laptop I had to find a different zoom percentage.

Operating System: Fedora Linux 42
KDE Plasma Version: 6.3.5
KDE Frameworks Version: 6.14.0
Qt Version: 6.9.1
Kernel Version: 6.14.9-300.fc42.x86_64 (64-bit)
Graphics Platform: Wayland
Processors: 2 × Intel® Core™2 Duo CPU     T9400  @ 2.53GHz
Memory: 3.7 GiB of RAM
Graphics Processor: llvmpipe
Manufacturer: LENOVO
Product Name: 6475R2G
System Version: ThinkPad T400

Thanks for reopening. I could reproduce _something_ thanks to the video you uploaded in the other ticket. These are my steps, can you please confirm that this is what we're talking about here?

Steps. See video here https://youtu.be/hwqxgo-iWY0
- Open big image (lets say >15 MB jpg)
- Zoom into the image
- Pan around the image

Noteworthy
- Effect is more pronounced the more pixels have to be rendered: higher screen resolution, big Gwenview window, big resolution pictures... 
- Reproducible on X11 and Wayland, on any fractional scaling level.

Thank you for providing a video recording.

Yes, that is what I'm talking about. The recording is set to 28 FPS according to YouTube "statistics for nerds", but I can still see the slow performance.

It's much more noticeable when using a high refresh rate monitors (120hz or more). 

You could also compare it to Loupe (https://flathub.org/apps/org.gnome.Loupe), the difference is night and day.

Allright thanks for confirming!

I will ask someone to change severity to wishlist since it's an optimization issue. Maybe there *is* a way to utilize a more efficient method here for drawing the content.

Please see Comment #5 for steps.