you need -n, otherwise it's trying to RDNS the IP's. It's a dumb default... chatting on the network without you asking while at the same time censoring the data the kernal was using... similarly "ls" might take forever (which matters if it's a big folder and you are piping it's output or just want |head) because it wants to sort (use -f to fix). The ls is a sensible default, often it's for human consumption, and the sort is way faster than a bunch of DNS lookups that could take an arb long time.

lsof has a good case to join coreutils.