Tested : 17 GB file compress to 6.5GB in 3 mins with 20 vcpu's
Same without pbzip2 -p20, 17 GB file compress to 6.5 GB in 17 mins
install pv if not present ( pv is optional ) to see progress bar
set SIZE=`du -sk directory | cut -f 1` ; tar -cf - directory | pv -p -s ${SIZE}k | /sbin/pbzip2 -ckv -p20 > directory.tar.bz2
set SIZE=`du -sk directory | cut -f 1` ; tar -cf - directory | pv -p -s ${SIZE}k | /sbin/pbzip2 -ckv -p20 > directory.tar.bz2