thanks for the vote of confidence, im no expert but i do however spend a good deal of time troubleshooting nvidia/optimus related issues.
gnome and nvidia dont work well together, or mutter to be more precise. there's a mutter workaround meant to work better with nvidia in the aur mutter-781835-workaround
it's worked for others but i never had a chance to test it since i dont use gnome for a while now.
thats alot, unless your talking about when your doing editing. general multitasking even with a good amount of browser windows open shouldnt break 4gb (and im being generous). if thats how much ram your using while doing general tasks you should really look into that.
now, let's see whats goin, please post:
mhwd -li
pacman -Qs "bbswitch|nvidia|nouveau|xf86-video"
ls -laR /etc/X11/
cat /etc/X11/xorg.conf.d/*.conf
cat /etc/modprobe.d/*.conf
cat /etc/modules-load.d/*.conf