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  • User (Old forums)
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    #20483 |

    I’m using a trial version of Xceed Zip for .Net v5.1. and am finding that compressing a file using LZMA + 256-bit AES encryption is taking a lot longer than expected.  Using Winzip v15 compressing a 250MB SQL bak file down to about 40MB is taking a little over a minute.  But with Xceed it’s taking around 5 or 6 minutes.

    I do realize that it’s not totally fair to compare the products, but the difference in compression time seems so stark that I’m wondering if there’s something wrong.  Six minutes is just so painfully slow on these small 250MB test files I’m throwing at it.

    Imported from legacy forums. Posted by Michael (had 1421 views)

    Diane [Xceed]
    Moderator
    Post count: 1353

    Hi Michael,

    Because our component is written in a .NET language, LZMA will never be as fast as a compiled, native implementation.

    Still, the difference is indeed stark in your case. Could you provide us the code snippet you used to perform the zip operation?

    Did you set the CompressionLevel to something like CompressionLevel.Highest? If so, that will slow down the compression significantly without much benefit in most cases. If you set it to CompressionLevel.Normal, do you get a better time?

     

    Imported from legacy forums. Posted by Diane [Xceed] (had 281 views)

    User (Old forums)
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    Post count: 23064

    Diane,

    Here is a code snippet.  When compressing our 235MB file, the result is 38MB (same as when using WinZip).  In my timing tests, XceedZip is consistently coming in at 4 minutes vs 1 minute for WinZip v15.  WinZip reports both resulting files to be LZMA/AES256.

    On a side-note, the file within the archive created with XceedZip.Net does not have a CRC listed.  Is that normal?

     

     

    private void MyCodeSample()
    {
        DiskFile bakDiskFile = new DiskFile(“c:\\intput.bak”);
        DiskFile zipDiskFile = new DiskFile(“c:\\output.zip”);

        ZipArchive zip = new ZipArchive(zipDiskFile);
     
        zip.DefaultCompressionMethod = CompressionMethod.LZMA;
        zip.DefaultEncryptionMethod = EncryptionMethod.WinZipAes;
        zip.DefaultCompressionLevel = CompressionLevel.Normal;
        zip.DefaultEncryptionStrength = 256;
        zip.DefaultEncryptionPassword = “SecretPassword”;  //Same complexity as our real password

        sqlDiskFile.CopyTo(zip,true);
    }
                
      

    Imported from legacy forums. Posted by Michael (had 339 views)

    User (Old forums)
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    Post count: 23064

    I think the lack of response tells me everything I need to know to make my purchasing decision.

    Imported from legacy forums. Posted by Michael (had 298 views)

    Diane [Xceed]
    Moderator
    Post count: 1353

    Hi Michael,

    I had escalated your request to the development team and am awaiting for a reply. As I have not yet received an update, I did not have anything new to post. I apologize for the delay it is taking and the inconvenience this is causing you.

    If your decision is final, then we will respect it and I will consider this request as closed. However, if you would still like to get an answer, please let me know and I will keep your request open. Thank you.

     

    Imported from legacy forums. Posted by Diane [Xceed] (had 1169 views)

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