Recently I’ve gave up Windows for Linux and installed Ubuntu with KDE Plasma desktop on my pc and laptop from 2007. It’s an i7 Intel processor with 8gb ddr ram so I thought it would be fine, but it seems quite sluggish. What distro could I use that would be faster and still fully functional? Thanks for your help in advance.
Try archlinux+i3wm. This is best thing happened to my laptop 💻
If you are an advanced user voidlinux is very good for laptops, in my experience without systemd you have faster boot timings.
Linuxmint with xfce, perfect.
It is, no doubt. xfce is lower though. In my 10 yo system xfce uses less ram than cinnamon.
Debian XFCE