If the Mac has a Retina display then I actually found XFCE runs worst of the various DEs at native resolution. Not in terms of resources but very choppy scrolling, video playback etc. Gnome and KDE Plasma actually ran better than XFCE for me on my 15” 2012 retina.
Presume it’s some kind of graphics acceleration thing, not 100% sure.
The tiny thumbnail for this looked like a belly button on my phone, had no idea what I was tapping on at first