I switched to Kubuntu 25.10 on my desktop from Windows 10 and every since, I’ve noticed that Linux on my primary monitor has felt very choppy with a low FPS. Animations are choppy and slow. As soon as I drag it to my second monitor, everything is faster and has higher FPS. This doesn’t happen on Windows. testufo.com shows ~20fps on the problematic monitor I also haven’t noticed this behavior with any other programs. There are spikes to 50fps and smoother animations when I open the Firefox menu, but then it goes back to 20fps. Chromium on the same monitor is faster and shows 50+fps. Games on this monitor also are higher fps
The primary monitor is configured to 60Hz, the second monitor is 143.97Hz. I’ve got an Nvidia GeForce 2070 with the NVIDIA driver (open kernel) metapackage from nvidia-driver-580-open installed, 32GB of RAM, plenty of CPU, and no other programs or tabs open even.
What could cause this issue and how can I fix it?
Fractional scaling is a compositor issue, not a linux issue, so in this case kwin. But yes, fractional scaling in general is always problematic as there’s no way to cleanly multiply pixels by fractions, so you get wonky fonts, UI that doesn’t quite fit… and whatever hacks your compositor has on top to make it look better, it’s best to avoid it if possible and only increase the font size.