@Romidar Like everything, I guess it comes down to what you're using the system - i.e. browser - for. And yes, I realize the OS in this case is Win 10 and Vivaldi is the browser sitting on top of it.
In my case, what do I use Vivaldi for:
I browse the internet using a handful of Favourites or new sites accessed via specific URLs located from my default search engine (DDG).
I manage my email correspondence for two external accounts (one Yahoo mail, one Gmail)
I listen to music via Spotify or a selection of internet radio stations.
In terms of work, as I'm retired I do a bit of writing, sometimes direct to the blogging platforms I use (Blogger and Vivaldi.net).
And that's it. So for me KISS works perfectly well for me, and I have no doubt helps with stability in my case - not only of the browser but also in its interaction with Win10. When I set Edge up, I kept it just as simple, ditto for a while Firefox (although on both I used ad-block extensions) and I never had any issues with them either: no strange crashes, no screen locks, nothing weird at all, even after installing regular update packages.
Maybe I'm just lucky.....for 10 years or so.