LZFSE

LZFSE (Lempel–Ziv Finite State Entropy) is an open source lossless data compression algorithm created by Apple Inc.

[6] Neither LZFSE nor LZVN is tunable at runtime, although a few constants can be tweaked at compile time for the usual speed-ratio trade-off.

[1] Apple's LZFSE implementation uses a simpler algorithm called LZVN when the input is smaller than LZFSE_ENCODE_LZVN_THRESHOLD (4096 bytes).

In the open source reference implementation, Apple explains that LZFSE does not perform as well for small sizes, so LZVN is used instead.

[8] AppleFSCompression.framework (AFSC), the mechanism for quasi-transparent compression in HFS Plus and Apple File System, supports LZFSE and LZVN since OS X 10.9.