Let's do an informal #experiment here...
I have an #LXQt Arch install on an HP 15 Notebook PC, which has an Intel Core i3-4010U, 4 GB of RAM, and a Samsung 860 EVO Plus SATA SSD (if I recall correctly). We're going to test if using SDDM on #Wayland vs #X11 is going to make a difference in idle RAM consumption. No programs except Konsole & htop will be opened.
We'll test with the following setups:
X11 SDDM with X11 LXQt (Openbox)
X11 SDDM with Wayland LXQt (labwc)
Wayland SDDM with X11 LXQt (Openbox)
Wayland SDDM with Wayland LXQt (labwc)
Let's give it a shot!