SteamOS 3 is Steam big picture mode inside of gamescope (a standalone wayland mini compositor), without your KDE desktop running in the background. You still have bluetooth, wifi and whatever other background processes running, but if you want to use a video editor, use your terminal or something else not on Steam then you have the option to boot out of gamescope session and into desktop mode from the ‘Power’ menu option. In game mode you still have to deal with Steam being a webapp but with no other desktop programs running, aside from the game you’re playing.
SteamOS 3 is Steam big picture mode inside of gamescope (a standalone wayland mini compositor), without your KDE desktop running in the background. You still have bluetooth, wifi and whatever other background processes running, but if you want to use a video editor, use your terminal or something else not on Steam then you have the option to boot out of gamescope session and into desktop mode from the ‘Power’ menu option. In game mode you still have to deal with Steam being a webapp but with no other desktop programs running, aside from the game you’re playing.
OK, so the comment above mine is misleading. The difference in resources would be small as my DE and Compositor use negligible resources.