The Minipedia demo server is very small and very slow and there are so much completely unuseful daemons running on it.

Some of the stuff (with all the related dependencies) that can be safely purged/blasted to waste fewer resources:

gdm3
cups
pulseaudio
gnome-shell
gnome-*
avahi-daemon
wpasupplicant
modemmanager
evolution
libreoffice*