I guess I'm smart enough to install opensuse, but dumb enough that I somehow got slow pacman.
I kid you not, on my hardware zypper is the fastest between ubuntu apt, fedora dnf, and arch pacman. dnf was the second-fastest on my hardware, with apt and pacman being pretty sluggish
I've also used portage which was even slower, but probably not a fair comparison considering how much more complex it is.