Source is this video:
Windows Was The Problem All Along - Dave2D
We could obviously compare performance between windows and steamOS before on the steam deck, or between windows and Bazzite on other handhelds. But this is the first time we have had official windows and SteamOS builds for the same hardware.
They made an attempt. It’s called Windows RT. It’s a sandbox more locked down than iOS.
The Win32 desktop environment isn’t built to support stuff like “timer coalescing” for all the API calls which all the software is designed to run continously in the background. Changing how it idles would change so many things which all kinds of software depends on that it would barely be the same OS anymore.