From Gentoo Wiki
Bzip2 is a high-quality, patent free file compressor using the Burrows-Wheeler algorithm. Files are typically compressed to anywhere between 10% - 15% of their original size while maintaining a speed of roughly twice the speed of compression and up to six times the speed of decompression of the PPM compression family. Any machine with an ANSI C compiler should be able to support bzip2, making it a great choice for those who run systems with portable demands.
USE flags for app-arch/bzip2 A high-quality data compressor used extensively by Gentoo Linux
||Enable behavior to support maintaining /bin, /lib*, /sbin and /usr/sbin separately from /usr/bin and /usr/lib*|
||Build static versions of dynamic libraries as well|
After adjusting USE flags:
emerge --ask app-arch/bzip2
emerge --ask --depclean --verbose app-arch/bzip2