I ran all your commands above on Debian Buster (4-core i5 2500 from 2011, 8GB ram, SATA SSD). My /tmp apparently isn't a tmpfs mount. Results: http://paste.deb

I ran all your commands above on Debian Buster (4-core i5 2500 from 2011, 8GB ram, SATA SSD). My /tmp apparently isn't a tmpfs mount. Results: http://paste.debian.net/1072430/ http://paste.debian.net/1072430/ It took 54s to sort|uniq and 38s for the presorted dataset. EDIT: For the unsorted dataset: 35s for `sort --parallel=8 -u` and 37s for `sort --parallel=4 -u`.