May be your PC has low free RAM and it has low performance HDD for swap file? Then it could be like this: `Refreshing AUR` stage downloads a 9.3 MiB file and eats about 1.5 GiB of RAM memory
But here in testing branch you got the 11.0.2-6 version of libpamac initially, which takes about 900 MiB of RAM in case of my semi-garbage notebook listed there.