Minecraft wiki entry for Region_file_format, associated text: The system is based on McRegion,[2] a mod by Scaevolus, also known for his development of the Optimine project. The McRegion format was adopted nearly unchanged, except for the addition of a table of chunk update timestamps. JahKob has claimed that this format is up to 7 times faster than the previous system.[3] The difference in a world's total file size between the Region file format and the Alpha level format is negligible.