I've read this Q&A and I'm ready to try it with Xubuntu. That is, I'll go from Ubuntu to Xubuntu.

At this moment, my laptop is slow, even after the various optimizations. My question is whether this is the correct way to proceed.

sudo apt-get upgrade          # upgrade all existing packages to newest version
sudo do-release-upgrade       # upgrade system (takes some hours)   

sudo apt-get xubuntu-desktop   # switch to Gnome on login

Remove the ubuntu-desktop package (Which command should I use?)