From my experience, KDE can run well even on older computers. I have used KDE with only 2GB ram, a 10 year old dual-core Intel Celeron CPU, and an integrated GPU, and it runs rather well, if only a little laggy here and there. Of course, XFCE runs much better with that setup, though.

Just like a certain great philosopher said, “The sun is a deadly laser”

Does that make it an Australian pizza?