I’m a programmer and I still use Kate mostly for notetaking and configuration editing. I tend to use other editors like VS Code when I’m doing more involved stuff.

As a years-long Kate user, I’d assume the answer to most of those features is “no”. It’s still mostly a code editor, not an IDE.

Neat. I’ve been using kate as my standard text editor for years, mostly because of the session management and because you can give it a pretty minimalist interface with some configuration (something that similar editors like Geany tend to struggle with). I honestly didn’t know that there was a searchable tab list, I’ve been using alt+tab (which already has a much better UI than many other editors) but that definitely gets unwieldy when you have a ton of tabs open (which is always … don’t even ask how many browser tabs I have).

Measuring these uncustomized directly after booting is a pretty flawed metric, especially with something like KDE that has a lot of features that can be enabled or disabled. i.e. many features that are built into KDE might need external programs that are not included in the base install of LXQt or XFCE, and some stuff might get reused when you start opening LibreOffice, Firefox or a text editor (AFAIK this is definitely a thing if you use a lot of KDE/Qt applicatons). The desktop comparisons I saw during KDE 5.x had it at not that much more RAM use than XFCE, and I doubt this changed that much with KDE 6. Maybe something about Wayland, though? e.g. XWayland might eat additional resources. Also, the baseline RAM use seems really high when even XFCE uses 1.4GiB by default.

For the record, I use LXQt, not KDE.