Plasma is more lightweight than GNOME in terms of resource usage, so… (I use a tiling window manager, btw)

I’ve been using it for a long time. I’ve personally found that there is essentially no impact on gaming performance–or if there is, it’s so slight that it’s totally negligible on midrange hardware, especially with feral gamemode. It might be more impactful on low spec PCs, I would assume, but I’m not sure of that. In my case, it’s plenty lightweight and offers lots of customizability.

I used to feel that way as well, but things have changed and improved quite a bit.