Lbzip2 is a multithreaded utility for handling ‘bzip2’ compression, written by Laszlo Ersek. It makes use of multiple processors to speed up its operation and in general works considerably faster than bzip2. For a detailed description of lbzip2 see http://freshmeat.net/projects/lbzip2 and lbzip2: parallel bzip2 utility.
Recent versions of lbzip2 are mostly command line compatible with bzip2, which makes it possible to automatically invoke it via the --bzip2 GNU tar command line option. To do so, GNU tar must be configured with the --with-bzip2 command line option, like this:
$ ./configure --with-bzip2=lbzip2 [other-options]
Once configured and compiled this way, tar --help will show the following:
$ tar --help | grep -- --bzip2
-j, --bzip2 filter the archive through lbzip2
which means that running tar --bzip2 will invoke lbzip2.