Noita running in slow motion, especially when your hardware should be good enough to run it, seems to be a somewhat common issue that unfortunately seems to have very few good solutions. No matter how low your resolution, no matter if you're just chilling in the Holy Mountain with absolutely nothing going on onscreen, the game runs in perpetual bullet time, or sometimes goes back and forth between doing that and running normally, again for no explicable reason.
Some people recommend going into the game's settings file and changing the FPS to 30, but that didn't work, and for that matter it also messes with the game's physics and systems since it's all tied to framerate, so even if it did work it wouldn't be a very good solution. However, after doing a lot of scouring on the interwebs for solutions, I finally ran across a post suggesting to run the game with Feral GameMode. It turns out that this was the solution I needed, since (I'm guessing) some issue with how the CPU was being managed was causing my game to slow down (even when I had freshly restarted the computer and there were no other programs running beside Steam).
If you are having issues similar to mine, this will hopefully also work for you.

Taken from the Feral GameMode website[feralinteractive.github.io]:

GameMode is a daemon/lib combo for Linux that allows games to request a set of optimisations be temporarily applied to the host OS and/or a game process.

GameMode was designed primarily as a stop-gap solution to problems with the Intel and AMD CPU powersave or ondemand governors, but is now host to a range of optimisation features and configurations.

I won't be going to in-depth on the subject since Gamemode is available in the repositories of most mainstream distributions and can be easily installed through the package manager, which you should most likely already know how to do. If you can't see it in whatever package manager GUI your distro has (if applicable) you can install it the leet hacker way through the terminal.

For example, if you're an Ubuntu-based distro user

If your specific distro does not include Gamemode in its repository, then you will have to build it from source. Instructions for doing so are found here.[github.com]

To run Noita with GameMode, all you have to do is right click on the game in your list, go to "Properties...", and in the launch options in the General tab, just type in


Just as shrimple as that.

Running Noita with GameMode should probably fix it without needing to fiddle with any configuration files, but if you need/want to, you can edit the gamemode.ini file which should be found in either $HOME/.config or usr/share/gamemode. There are explanations for all of the settings found within the .ini file itself.

Hopefully this will fix the problem for you like it did for me. If it does, then happy Noitaing!