Terrible performance on Intel

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1

Recently I’ve been experiencing extreme slow downs on my system and it does not seems like it’s consistently related to the actual system usage. Here’s my setup:

OS: NixOS 25.11 (Xantusia) x86_64
Host: 83AF (IdeaPad 1 14IAU7)
Kernel: Linux 6.19.6
Shell: zsh 5.9WM: Sway 1.11.0) (Wayland)
CPU: 12th Gen Intel(R) Core™ i5-1235U (12) @ 4.40 GHz
GPU: Intel Iris Xe Graphics @ 1.20 GHz [Integrated]
Memory: 3.73 GiB / 15.35 GiB (24%)
Disk (/): 29.76 GiB / 67.45 GiB (44%) - ext4
Disk (/home): 150.75 GiB / 168.64 GiB (89%) - btrfs

I came from Arch and my workflow is still pretty much the same, but the system never slowed down to that point in any other distro, in fact, it didn’t even on NixOS until a couple weeks ago.

The stopping point was when I was using Floorp (from floorp-unpacked, it’s a Firefox fork) and I noticed that it was struggling even to load YouTube at the speed I’m used to. Toggling hardware acceleration off made it even worse, I ended up finishing the video on Chromium (from ungoogled-chromium), as since it seemed a bit more stable, after that I went back to Floorp and it was OK.

Today I played a lot of Minecraft LCE through Lutris/wine and it was running fine at 60fps with a moderate render distance. I finished my session and when I went back to play with a friend it was unplayable, single digit FPS.

It may be related to the upgrade I did a few days ago, but since I don’t have storage to afford keeping two generations in different versions for too long, I ended up deleting it before I could notice any difference.

It’s good to note that I have thermal issues with this laptop and I’m using thermald, but the performance hit was never that high and the CPU temps are OK, not even reaching the thermald limit (it’s from 38-40°, the limit is 50°). What makes me think it’s not the overheating issue is that I played Minecraft for about 6 hours and it worked fine, but then I decided to play again it didn’t.

I don’t really know what to do because I’ve never hit such instabilities on any other distro, the PC just starts lagging when I’m doing moderate work and it’s unusable. Any tips/clues?

Update: signal-desktop seems to randomly slow the system down too.

2

Sounds like memory. Keep some way to look at system resources open and check the stats. 16GB isn’t a lot, I can imagine minecraft or big browser sessions guzzling that up these days.

Logs from journalctl --boot -e after you start noticing the slowdowns would help, too.

This is likely not NixOS-specific, but simply comes down to how you’re using your system.

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I’m very concerned with memory usage, so I keep only two or three tabs at the same time. Floorp also kills tabs when I don’t use them. Also the memory/CPU usage is displayed in my taskbar, so I would notice any spike in usage.

When the system is slow htop reports normal usage of RAM, yesterday was using about 30% when I was browsing the web. Also when the PC starts lagging the CPU usage is 100% in one or two cores and the rest is fine.

Right now I tried to stress the system doing the same things I did yesterday but everything was smooth. Things I ran at the same time:

  • 4k video playback on YouTube + some other tabs I’m sure are loaded (WhatsApp Web, Instagram, Jellyfin)
  • Minecraft LCE through wine
  • Firefox in a Fedora Live VM (QEMU), 6GB of RAM allocated
  • Signal Desktop (electron)

This resulted in 70% of CPU usage and about the same in RAM, both more than when the system is sluggish, but there were no signs of slow downs. The CPU is not that powerful but it always handled multitasking gracefully for my use case.

I’ll make sure to run this when I encounter the issue again.

I forgot to mention and I don’t know if it’s the same issue, but OBS studio will slow down the system the same way I described, and closing does not solve anything, only rebooting.

Probably, I made this post here to make sure I’m not missing something obvious in my setup, I’m new to NixOS.

4

That’s pretty normal, most software still barely does any multiprocessing, and you’re unlikely to have more than one or two processes actually doing real work on a consumer system.

The 30% disparity between usable and not probably comes down to something like the CPU getting stuck in a low pwer state. Next time you see this, reboot fully with the system plugged into AC power. If that solves it, you found your culprit.

I’ve mostly seen this kind of behavior with laptop-mode and other such power optimization utilities.

You may want to try setting up hardware acceleration for media decoding. Software decoding is unnecessarily taxing your CPU.

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5

Thank you, it’s probably something related to my power profile since setting powerprofilectl to balanced when the system starts to lag solves the problem partially, but it’s at least usable and probably caused by my usage, as you noted.

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