I was playing around with an old laptop dual booting Fedora KDE and W11. And Fedora on fresh boot was using the same/more ram than 11.

Windows compresses RAM these days, not sure if Fedora does by default. Also, by itself Windows is surprisingly RAM efficient. I think it’s a holdover from Windows 8 which was developed for tablets when Microsoft tried competing with iPads.

The problems arise when web views like the news widget load. Then all the past optimizations no longer matter.

Also I don’t think KDE even uses more RAM than other DEs that are designed to be lightweight. Last time I compared, it used the same or less memory as LXDE.

Firefox without any website loaded uses more RAM than a full Plasma session.