I convinced my wife to dual booting Linux Mint. She uses it every now and then, but she primarily still uses Windows 10. I hope she will abandon it once she sees this. She absolutely detests ads of any kind.
Thank you all for your ideas, I managed to solve the problem. It was somewhat hardware related, but not really.
I was using BTRFS, which creates a lot of write amplification and aged SSDs don't handle that well. According to a study from 2017, btrfs can cause up to 32x write amplification, absolutely hammering its performance: https://ar5iv.labs.arxiv.org/html/1707.08514
I converted my system to RAID0 using EXT4 and the stutters and freezes are gone.
Plasma freezes during high disk activity (solved)
I have a few dodgy cheap SSDs, so I'm not surprised by slow I/O performance in general. But my Plasma desktop frequently freezes for 1-3 seconds (including the cursor!) whenever there is high IO load, for example while installing a Steam game.
Updating the screen should be completely independent from I/O, shouldn't it? Is there anything I could've misconfigured in my Arch Linux? I'm running Plasma 6.1.4 in Wayland.
can’t afford to buy a house
My simple solution to this problem: Just don't buy a house then. Just accept you'll never own real estate and move on.
Try searching it on https://btdig.com/, a DHT search engine. Most of the torrents there are very old and have barely any seeds. Be patient. The last thing I downloaded from there took 1-2 weeks to complete.
Permanently Deleted
That's what I do. I seed for as long as it remains on disk.