Currently the ChromeOS build system is usually using pbzip2 for compressing files into bz2 format. However lbzip2 is probably a better choice because of:

 - lbzip2 is usually faster and producing better compression rate, with the cost of taking more memory.
 - lbzip2 is pure C and does not rely on libstdc++ (less dependency)
 - GNU tar has officially supported lbzip2, not pbzip2

So we should consider moving from pbzip2 to lbzip2.