Gnome-software, which is one of the top memory consumers, is being loaded at startup and thus decreasing boot time.
I rarely use gnome-software, and on most boot-ups it is useless. However there is not an entry at start-up apps, not even after showing hidden startup apps (https://help.ubuntu.com/community/ShowHiddenStartupApplications). Also, I haven't found any gnome-software-related process from systemd-analyze to disable it with systemctl.