This applies when RAM is used as temporary cache or something that can be instantly freed the moment it is needed otherwise. This doesn't really work for justifying higher RAM use by KDE, unless you would never need that RAM for anything else anyway.

I use KDE because it is good, though. 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.

"i paid for the whole RAM imma use the whole RAM"

–me in 2010 using console commands to turn off all the particle effects in Portal so that I could boost my fps to ~20 w/ minimum settings (the laptop did not have a graphics card lmao)

It's just really oversimplifying memory usage. OS designers had that same thought decades ago already, so they introduced disk caching. If data gets loaded from disk, then it won't be erased from memory as soon as it isn't needed anymore. It's only erased, if something else requests memory and this happens to be the piece of "free" memory that the kernel thinks is the most expendable.

For example, this is what the situation on my system looks like:

free -h
               total        used        free      shared  buff/cache   available
Mem:            25Gi       9,8Gi       6,0Gi       586Mi       9,3Gi        15Gi

Out of my 32 GiB physical RAM, 25 GiB happens to be usable by my applications, of which:

• 9.8 GiB is actually reserved (used),
• 9.2 GiB is currently in use for disk caching and buffers (buff/cache), and
• only 6.1 GiB is actually unused (free).

If you run cat /proc/meminfo, you can get an even more fine-grained listing.

I'm sure, I could get the number for actually unused memory even lower, if I had started more applications since booting my laptop. Or as the Wikipedia article I linked above puts it:

Usually, all physical memory not directly allocated to applications is used by the operating system for the page[/disk] cache.

So, if you launch a memory-heavy application, it will generally cause memory used for disk caching to be cleared, which will slow the rest of your system down somewhat.

Having said all that, I am on KDE myself. I do not believe, it's worth optimizing for the speed of the system, if you're sacrificing features that would speed up your usage of it. Hell, it ultimately comes down to how happy you are with your computer, so if it makes you happy, then even gaudy eye-candy can be the right investment.
I just do not like these "unused RAM is wasted RAM" calls, because it is absolutely possible to implement few features while using lots of memory, and that does slow your system down unnecessarily.

While I agree with you, it's not like GNOME consumes so many ressources that it affects the average person's experience.

Personally, I think GNOME is much more self explanatory. Whatever environment you come from, even if you have no computing experience at all, you will probably get stuff done with GNOME.

With Plasma, I noticed that people with low tech-skills struggle a lot more, because they are less crazy about making everything super duper extra obvious (especially how to configure stuff)

For what it's worth, I was in a similar boat. I wanted to try WMs/compositors, but the configuration seemed daunting. Then I gave Dank Material Shell a try and it just configured the vast majority of the system very nicely. I still had to change some window rules in the config file, but even that has a GUI now. I also heard great things about Noctalia, and I'm sure there are others as well.

I still think KDE is a top-tier option, to be clear. :P And adding tiling to KDE is also a great way to get the best of both worlds, just from the other direction.

The one thing I have to make leaner on every clean Plasma install is KSearch or what it's called. searching for programs is WAY slow with all the search functionality enabled

All main desktop environment users triggered in 3...2...1...

But seriously, as a KDE Plasma user, I have to note it's extremely customizable. It doesn't have to look or behave like Windows at all, it's just a default.

An entirely different look? Sure! All sorts of completely customizable shortcuts? Yep! Tiling? If you so wish!

The thing that made Plasma my forever choice is that whatever I want to make it, it delivers. It has settings for everything.

Here are just two examples of the non-standard KDE looks by the way:

Yeah I dont get the obsession with optimization

right? I thought twms were almost exclusively for workflow efficiency only and this was like 15 years ago lol

KDE Plasma can do that, too, via a KWinscript: https://codeberg.org/anametologin/Krohnkite 🙃

On a more serious note, this is a genuine recommendation. I've been using Krohnkite and similar scripts for a few years now, and they're absolutely fine, especially since Plasma 6 introduced a native, manual tiling mechanism, which they just have to configure.
Especially for newbies wanting to try out tiling window management, without having to figure out a minimalist environment like a bare window manager, this is a great entrypoint IMHO.

What do you do to it so it becomes unstable?

KDE is stable in my experience, but I don't enjoy the window management and the shitloads of embedded packages. Now I'm on river for the time being.

I, too, hate aesthetics

hyprland looks good for screenshots but as soon as you update your system you'll see that beautiful error box on top of your screen

Hyperland is the definition of a tiling WM thats just as heavy if not heavier than KDE (depending on your config)

I used Niri with KDE apps for a month recently and liked it a lot. Niri is easiest to install already configured as a useable desktop using Dank Linux or Noctalia.

If you like PaperWM, you will love Niri.