In early November we delivered benchmarks of EXT4 vs. Btrfs on an early Linux 2.6.37 kernel as our latest round of tests comparing these two leading Linux file-systems. There were some changes in the Linux disk performance with these file-systems using the latest Linux kernel code, but overall it was not too interesting. However, as the Linux 2.6.37 kernel does introduce a new mount option for Btrfs, the space_cache option, we decided to explore its performance in today's article.