![]() The speed for LZMA/LZMA2 compressing was increased by 8% for fastest/fast compression levels and by 3% for normal/maximum compression levels.7zip 18.02-18.05 used only one CPU thread for bz2 archive creation.The bug in 7zip 18.02-18.05 was fixed: there was memory leak in xz decoder.The speed for LZMA/LZMA2 compressing was increased by 3-10%, and there are minor changes in compression ratio.Encryption strength for 7z archives was increased: the size of random initialization vector was increased from 64-bit to 128-bit, and the pseudo-random number generator was improved.There is 2% speed optimization in 7-Zip benchmark’s decompression.The existing code of x86/圆4 AES-NI was improved also.7-Zip now can use new x86/圆4 VAES (AVX Vector AES) instructions, supported by Intel Ice Lake CPU.The speed of zip AES encryption and 7z/zip/rar AES decryption was increased with the following improvements:.the speed of key derivation for encryption/decryption in 7z/zip/rar archives.the speed of encryption/decryption in zip AES,.the speed of SHA-1/SHA-256 hash value calculation,.7-Zip now can use new x86/圆4 hardware instructions for SHA-1 and SHA-256, supported by AMD Ryzen and latest Intel CPUs: Ice Lake and Goldmont.7-Zip now can unpack files encoded with Base64 encoding (b64 filename extension).bzip2 decoding code was updated to support bzip2 archives, created by lbzip2 program.Minor speed optimizations in multithreaded LZMA/LZMA2 compression for Normal/Maximum/Ultra compression levels.Fast level (-mx3) : hc5 match finder with 4 MB dictionary.Fastest level (-mx1) : hc5 match finder with 256 KB dictionary.The compression ratio was improved for Fast and Fastest compression levels with the following default settings:.7-Zip now supports new optional match finders for LZMA/LZMA2 compression: bt5 and hc5, that can work faster than bt4 and hc4 match finders for the data with big redundancy.If the switch -ssp is specified, 7-Zip doesn’t allow the system to modify “Last Access Time” property of source files for archiving and hashing operations. The speed of PPMd compressing/decompressing was increased for 7z/ZIP/RAR archives. ![]() It allows to increase the compression speed for big 7z archives, if there is a big number of CPU cores and threads.
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