This nice tool really is amazing:

Pigz is a parallel implementation of gzip and can be used like gzip.
As it is able to spawn mutiple threads it is much faster than the single-threaded gzip.

Usage:

pigz -p 8 file # compresses file to file.gz using 8 threads
pigz -p 8 -d file.gz # decompresses file.gz to file using 8 threads

pv file.gz | pigz -d -p 8 > file # decompresses file.gz to file using 8 threads and a nice progress bar using pipe view :-)