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From: Boaz Stolk <>
To: "" <>
Subject: compression and speed
Date: Tue, 29 Mar 2016 14:00:35 +0000



What is the reason for libzip’s poor performance when compressing/closing an archive?

I did some tests and compared the results of the default zip tool on my system (from Info-ZIP) with the libzip provided tool ‘ziptool’ and a Python script.

The difference surprised me; libzip is about 2.5 times slower than both Info-ZIP and Python!


Since all three use zlib for DEFLATE compression, how can this big difference be explained? Is libzip really that slow!? Can this be reproduced?






$ time zip source.bin

  adding: source.bin (deflated 47%)


real 0m1.675s

user 0m1.059s

sys  0m0.616s

$ time ziptool add_file source.bin source.bin 0 17856084


real 0m4.308s

user 0m4.027s

sys  0m0.277s


$ time python -c "import zipfile; zf = zipfile.ZipFile('', 'a', zipfile.ZIP_DEFLATED); zf.write('source.bin'); zf.close()"


real 0m1.701s

user 0m1.246s

sys  0m0.444s


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