I recently moved from KDE to Cinnamon, both using Funtoo and the same configuration. Cinnamon seems to take a lot more memory altogether and I now have to upgrade from 16 to 32 GB RAM to be able to run 2 users (my private and company users). Memory used with the same programs as in KDE consumes around 13GB and once in a while some program dies due to out of memory. With two loged in users the Cinnamon process consumes 1.2 GB RAM by itself.
The main differens between KDE and Cinnamon is how LibreOffice works. It is clumsy and slow in KDE built for KDE and noticeably faster built for GTK in an GTK environment. I am in general quite found of KDE themes but Adwita is the theme for LibreOffice and Inkscape - makes much more sense.