df-decompress

A Dwarf Fortress save in an uncompressed tar is 166,123,520 bytes (158.4 MiB). Compressed using xz, region2.tar.xz is 156,374,900 bytes (149.1 MiB). That's 94.1% of the original size.

The same Dwarf Fortress save is 1,296,906,240 bytes (1236.8 MiB) when decompressed using this program before archiving. Compressed with xz using the same settings, the result is 85,715,988 bytes (81.7 MiB). That's 51.6% of the original size.