gzip vs. pigz vs. bzip2 vs. pbzip2

Shortly after the last benchmark, I came across pigz (parallel gzip) and a bigger (real-world) task to complete:

$ time gzip -c file.tar > file.tar
real     41m52.636s
user     33m58.392s
sys       2m26.903s

$ time pigz -c file.tar > file.tar.pigz
real     18m34.894s
user     54m07.784s
sys       3m47.910s

$ time bzip2 -c file.tar > file.tar.bz2
real    838m47.771s
user    830m48.621s
sys       2m18.429s

$ time pbzip2 -c file.tar > file.tar.pbz2
real     58m06.466s
user   1748m17.785s
sys       4m49.537s

$ ls -lhgo
-rw-r--r--   1  15G Jun 24 02:03 file.tar
-rw-r--r--   1 598M Jun 24 22:10 file.tar.gz
-rw-r--r--   1 600M Jun 24 21:02 file.tar.pigz
-rw-r--r--   1 304M Jun 25 12:44 file.tar.bz2
-rw-r--r--   1 306M Jun 25 13:42 file.tar.pbz2
Hardware: Sun SPARC Enterprise T5120, 1.2GHz 8-Core SPARC V9, 4GB RAM