Zathura and related packages like Zathura-pdf-mupdf are not in artix's repos. Therefore i followed this guide: https://wiki.artixlinux.org/Main/Repositories#Arch_repositories . However, while in packages in artix's repos i usually get speeds around 9MiB/s, when downloading zathura-pdf-mupdf, the speeds were around 250 KiB/s. This is probably not a big deal since most packages i need are in artix's repos already, but i'm curious why these speeds were so different.
Use rankmirrors (https://wiki.archlinux.org/title/Mirrors#List_by_speed).