This was discussed previously. Have a look there.
@Thenujan that was a long time ago. Nowadays it’s just a question of taste and the differences are less than 1% between the two. If you want a “minimal” desktop experience, the Manjaro LXQT spin is the one to go for…
Having said the above, KDE has a lot of optional components like Magic Lamp, Wobbly Windows, fading pop-ups, Translucency, … so if you turn everything ON, yes, KDE will use more CPU and more RAM than XFCE…
