It’s not a cardinal sin, it’s called being a brave pioneer :)
Anyway, fwiw I’ve noticed something similar where steam just (re)starts all of a sudden while playing. Like I notice the game gets sluggish, then focus changes to the steam client, complete with the “new offerings” sale popup that comes when starting steam. And I did have steam overlay UI freeze completely recently but restarting the game and steam fixed it.
Kubuntu 22.04, X11, nVidia 3060 with 525 driver
In addition to the CPU throttling itself due to thermals like you said, you should also be aware that all Ubuntu’s are replacing more and more traditional packages with snaps for an increasing number of applications.
Step 1 (by the system) of opening a snap application for the first time (since boot) is to extract the compressed snap image, which makes startup time significantly longer (like several seconds for something you would expect to be instant). Once the application is started performance should be the same as if the application had been installed as a traditional .deb package.
You should also consider adding flatpak support and flathub. Applications installed as Flatpaks generally integrate better in the desktop than snaps, and flathub has a large and growing selection of apps. The flathub website has a few command lines you can copy-paste to enable flatpak and flathub support, then apps from Flathub will show up in the Discover app store.
Personally I use Kubuntu and use both Flatpak and snap apps, but generally prefer flatpaks when they’re available. And any software where I don’t care about having a recent version I install as a traditional package because it’s more lean
In addition to everything else said here, what has crystallized over the last year is how good it feels that Linux and other open source initiatives are Enshitification-proof
This I believe is a big part of what give the warm and fuzzy feeling when using open source software and website. Generally everyone involved wants to make something good, without looking towards IPOs or the next quarterly revenue at the cost of the software
(Sure controversies happen, but they are generally few and far between, and open source licensing ensure forking is a viable last resort, like with LibreOffice and Nextcloud)
That’s pretty cool, and nice to have the steam UI consistent with the rest of the desktop if you’re on gnome.
It’s also a bit ironic given how libadwaita was kinda born out of a desire of some developers to not have their apps themed https://stopthemingmy.app/
They were too preoccupied on wether they could, they never stopped to question wether they should