bzip2 is a free, multi-threaded compression utility with support for bzip2
compressed file format.

lbzip2 can process standard bz2 files in parallel. It uses POSIX threading
model (pthreads), which allows it to take full advantage of the symmetric
multiprocessing (SMP) systems.  It has been proven to scale linearly, even
to over one hundred processor cores.

lbzip2 is fully compatible with bzip2 -- both at file format and command
line level.  Files created by lbzip2 can be decompressed by all versions
of bzip2 and other software supporting bz2 format.  lbzip2 can decompress
any bz2 files in parallel.  All bzip2 command-line options are also
accepted by lbzip2.  This makes lbzip2 a drop-in replacement for bzip2.

WWW: http://lbzip2.org/