Electron.
While I’m singing the praises of Electron apps, I should also praise the memory efficiency of Catalyst apps, especially Apple’s own. 1.5 GB for a single-window app.
@gruber Catalyst apps are native apps using native APIs, so whatever News is doing, I don't expect it would use any less with a different technology; it probably has a lot of WebKit going on, to be fair, and whatever you're caching
@stroughtonsmith I know it's not the nature of Catalyst in and of itself to leak memory, but I think what happens is that apps written primary for iOS can get away with memory leaks because they get paged out in the background when necessary. They're not written to be running non-stop for days (or even weeks).

@gruber @stroughtonsmith They also end up in compressed memory (essentially paged out) or evicted entirely from memory with only a screenshot of the screen remaining (so you see something in the app switcher).

Most apps are written to take that into account, but on macOS, the model is different and an app's state is much more visible than the app switcher: it would be weird if the News app just randomly disappeared from the Dock, for example.