@VD15
I'm guessing whatever mirror it checks by default is slow for you, so maybe you should look into that. For me it works just fine, so I never had to tweak anything there.
@VD15
Try running:
sudo pacman-mirrors --fasttrack && sudo pacman -Syyu
It should speed test all available mirrors and keep the fastest ones.
Make sure to backup /etc/pacman.d/mirrorlist