This new release improves performance in general. It adds a new storage method for the data that is stored. Previous lessfs versions would store the data in tokyocabinet. The new file_io backend allows to store the data in a regular file or even a raw device (not recommended).
The file_io backend allows lessfs to store larger amounts of data with more modest memory requirements. The file_io backend should give similar performance when compared to tokyocabinet.