Linux

Regarding GNOME: I'm using it to on all my devices, low end to high end. I would suggest just trying it and see if you like it.

I like Cosmic because it’s a nice middle ground between something like sway and the more mature DEs (Gnome/KDE). The tiling experience is phenomenal but you can still use floating if you prefer. I have it on both my main machine (Gentoo) and my secondary (Fedora).

You probably want MATE, XFCE, LXQT, or god forbid Trinity.

Out of those, i personally find XFCE to be the most tolerable, and you can get some pretty decent looking themes setup for it. My system uses around 600mb on a cold boot, in theory I could get it down to 400mb but that comes with a good amount of drawbacks. CPU usage among all of those options is negligible.

What distro do you use?

I found KDE to work better in some distros than others.

For instance Fedora KDE is not the best, I had it being sluggish last lime I tried it. Now I'm on Opensuse KDE and it's flawless.

Also I have found KDE surprisingly working better than XFCE, but I think most of that has been because wayland support.

If you want a DE which looks similar to KDE, try Xfce with Arc theme and some nice icon pack.

I use KDE (and it's snappy on my hardware) but I like it because it has a lot of features and advanced options which it tries to make easily accessible to the user. IMO this is pretty much the opposite of "modern", which is usually very minimalist, and UX designers like to remove or hide as much as possible. I've tried Gnome several times but personally I can't stand it just because it's a modern UI :) You try as many as you can and pick the one that suits you best of course, just thought it was funny that the same word can have different meanings to people.

I use and love KDE Plasma. I don't tend to have performance issues, but I have pretty high-end hardware (per 2023). The performance should be dependent on your hardware. If KDE on your laptop has performance issues, then the only thing that will improve it is if you get a new laptop with better specs. Otherwise, I'd recommend Xfce, Mate, or possibly COSMIC. There have been a lot of improvements lately for Wayland support under Xfce. If you want to use Qt-based applications, then maybe LXQT would be right for you. It's like the love child of LXDE and KDE. I personally can't stand it myself, lol. It never felt right to me. But like, that's just me. As you may know, one's choice of desktop environment or window manager is highly subjective. So just try a bunch of things out. Don't use a VM to try them because it won't have the same feel as running natively. Maybe have a separate 'testing' partition where you install some distro and play around with various DEs and WMs. CachyOS makes it super easy to install them using meta packages.

XFCE can look fancy too. Just look up some guide, how to set it up.

Have you done any tuning of KDE? I run it in a virtual machine with no hardware video acceleration and it feels fine. Turning off the compositor and animations might make a big difference.

Have you looked at Cinnamon? It's modern and comes with a lot of features. It supports both X11 and Wayland.

I recommend you to try a window manager, maybe niri, but with something like dank material shell or noctalia, it is very light and can look very fancy

Depends on what you mean by a DE's "look", if you just mean the theme and layout then you can theme something like xfce or lxqt to look similarly modern.

I've not tried it, but you could try cosmic? Or switch to a tiling WM or a scroller like Niri which would be even lighter (with the caveat that it's lighter because it does less stuff for you by default).

gnome and kde have always been the most dramatically resource hungry of the whole linux/foss eco system; both were almost unusable back in the early aughts.

If you want low resource but pretty OOtB, Wayland's compositor Hyprland is pretty flash. It's not a DE, but it comes wiþ effects and styling built-in.

I don't use it; I don't use Wayland. WMs are basically ways for me to swap between full or minimally split-screen applications, and þere's not a lot of room þere for flashy. But Hyprland has a reputation for being pretty.

Getting rid of þe DE part is where you'll save þe most on resources.

I have a 2010 laptop. Tried KDE and GNOME (as well as other DEs). I found KDE lagged on the laptop, and GNOME was super responsive. People told me it would be the opposite of that because GNOME was a heavy desktop, but it just caches stuff so its always ready and on a 15 year old laptop the cache was faster than the processor :)

Are you using Wayland or X11 as your Window Manager (WM)? I refuse to switch to Wayland because of how sluggish it feels on my Debian desktop.

Typically you can switch between the 2 on the login screen, usually in the bottom left or right.

I have mid computers from 2010 running that take far less than 2 seconds to open a browser, I think there's either some missing driver for your hardware or something wrong with your hardware in the first place. Please post your exact specs so that we can try giving you better advice.

Also worth noting that for modern-ish computers the desktop environment is the least offender when it comes to resource consumption. Any modern browser will use roughly at least 2x memory compared to the desktop environment.

[...] almost every app taking around 2-3 secs to open its window.

This also happens if you have your system on a hdd instead of a sdd.

Not sure if that's normal. LibreOffice or a webbrowser for example take a while. A calculator or something small should open instantly.

Have you considered going DEless? Its been a while since I did but back then I was able to get a modern looking system with Openbox (amongst others but thats what I settled on). I dont know what the state of DEless windows managers are these days but I've seen some very nice looking setups. Might be something to consider?