cjwatson@pepo:~$ zcat /srv/launchpad.net/ubuntu-archive/ubuntu/dists/xenial/universe/binary-amd64/Packages.gz >Packages
cjwatson@pepo:~$ time bzip2 -9c Packages >/dev/null

real    0m6.021s
user    0m5.924s
sys     0m0.036s
cjwatson@pepo:~$ time xz -6c Packages >/dev/null

real    0m19.531s
user    0m19.333s
sys     0m0.072s