Gnome and KDE plasma or whatever are horrible steps back in my experience. Laggy or slow loading of content in apps such as their app catalogs or hitching and lockups feel gross on a capable modern system even with 24gb of ram. Windows 11 isn't much better honestly where I relate to the video showing Win2k vs Win11 and apps take forever to load now.
Sure they are pretty looking but so was stuff like Aero which felt faster on worse hardware so what is going on? I feel like around the mid 2000s we went down the path of putting heavy, slow web-like user interfaces into the OS and brought everything down with it in favor of the scalability of DPI and easier (?) development. It's not really the OS either it's the apps. We've been making trade offs at the cost of usability and speed.
Some of the lighter DEs have problems too. Just about all of them take an extra beat or two to display their start menu equivalents for example, which feels like it’s probably a solvable problem considering that systems of yore could do the same with almost no delay on very limited hardware.