I’m not that comfortable with Xcode, but I just built two versions of this tool, one direct from GitHub, one (called lzfse2) that calls the Compression library on Mac OS X. Typical timings on my system are:

    > time ./lzfse -encode -i webster -o webster.lzfse

    real    0m0.945s
    user    0m0.864s
    sys     0m0.062s

    > time ./lzfse2 -encode -i webster -o webster.lzfse2

    real    0m0.803s
    user    0m0.715s
    sys     0m0.072s


    > time ./lzfse -decode -i webster.lzfse -o /dev/null

    real    0m0.133s
    user    0m0.091s
    sys     0m0.036s

    > time ./lzfse2 -decode -i webster.lzfse2 -o /dev/null

    real    0m0.083s
    user    0m0.053s
    sys     0m0.025s

So, the version that ships on Mac OS X seems to be faster (10% at encoding, 35% at decoding) than what this source and makefile produce. I don’t think that has to do with my way of building them, as I used the makefile (which uses -Os) to build the original tool, and any compiler flags will not have much effect on the one using the Mac OS X library.

Worryingly, the two versions also produce different files (12,209,496 bytes for the GitHub code, 12,234,159 bytes for the library on Mac OS X 10.11.5), but they can decompress each others files and produce the original file.