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Here are some tests.
time 7z a -tzip -mx=0 python-0.zip $(find Lib -type f -name '*.py') >/dev/null
time 7z a -tzip python.zip $(find Lib -type f -name '*.py') >/dev/null
time 7z a -tzip -mx=9 python-9.zip $(find Lib -type f -name '*.py') >/dev/null
time 7z a -tzip -mm=bzip2 python-bzip2.zip $(find Lib -type f -name '*.py') >/dev/null
time 7z a -tzip -mm=bzip2 -mx=9 python-bzip2-9.zip $(find Lib -type f -name '*.py') >/dev/null
time 7z a -tzip -mm=lzma python-lzma.zip $(find Lib -type f -name '*.py') >/dev/null
time 7z a -tzip -mm=lzma -mx=9 python-lzma-9.zip $(find Lib -type f -name '*.py') >/dev/null
time 7z t python-0.zip >/dev/null
time 7z t python.zip >/dev/null
time 7z t python-9.zip >/dev/null
time 7z t python-bzip2.zip >/dev/null
time 7z t python-bzip2-9.zip >/dev/null
time 7z t python-lzma >/dev/null
time 7z t python-lzma.zip >/dev/null
time 7z t python-lzma-9.zip >/dev/null
wc -c python*.zip
Results:
 pack* unpack size
 time time (MB)
store 0.5 0.2 19.42
deflate 6 0.4 4.59
deflate-max 40 0.4 4.52
bzip2 6 2.1 4.45
bzip2-max 79 2.0 4.39
lzma 37 0.7 4.42
lzma-max 62 0.7 4.39
*) For pack time I take user time because 7-zip well parallelize deflate and bzip2 compression.
As you can see, a size difference between maximal compression with different methods only 3%. lzma decompress almost twice slower then deflate, and bzip2 decompress 5 times slower. Python files are too small to get benefit from advanced compression.