3 ms·

But slower.

• lifthrasiir 5y ago
  It depends on which time you measure. 7zip's LZMA2 is, like most LZ algorithms, asymmetric that it is quite fast to decompress no matter how much you spend on the compression. By comparison RAR uses PPM in the highest setting, which is more or less symmetric so the compression and decompression takes about the same amount of time. When the target ratio is roughly same and high enough, LZMA2 is indeed slower than (RAR's implementation of) PPM for the compression but much faster for the decompression.
  • account42 5y ago
    > It depends on which time you measure. 7zip's LZMA2 is, like most LZ algorithms, asymmetric that it is quite fast to decompress no matter how much you spend on the compression. In fact, better compression with LZ formats often means faster decompression (at least compared to other settings of the same format) as there is less compressed data to pass through the expensive entropy coder (which itself has symmetric cost for encoding and decoding).
  • ComputerGuru 5y ago
    There is no world in which LZMA2 decompression can be considered “quite fast.” It’s decompression speed bears no resemblance to that of other LZ algorithms like LZ4 (which is definitely fast). https://www.opencpu.org/posts/brotli-benchmarks/ https://www.opencpu.org/posts/brotli-benchmarks/ Distributions have stopped using xz/lzma in favor of slightly inferior (size-wise) alternatives due to the time and memory decompression requirements of lzma.