c# RijndaelManaged 10 times sower than Java equivalent (AES/CFB8/NoPadding)

Question

While debugging the performance of my C# application I noticed that it's a lot slower than it's Java equivalence. After looking into it the problem seems to be caused by the encryption/decryption methods.

I am forced to use AES encryption with mode set to CFB8 and no Padding. For Java this is quite straight forward as I can use Cipher.getInstance("AES/CFB8/NoPadding");. In C# I found out that I need to use new RijndaelManaged(). After running tests with the same keys and same data it here are the results:

Java:

• Encrypt: 0.402s
• Decrypt: 0.480s

C#:

• Encrypt: 4.201s
• Decrypt: 3.671s

C# Cipher code:

    public ICryptoTransform enc;
    public ICryptoTransform dec;

    public AesCrypto(byte[] key)
    {
        enc = Generate(key).CreateEncryptor();
        dec = Generate(key).CreateDecryptor();
    }

    private SymmetricAlgorithm Generate(byte[] key) {
        RijndaelManaged cipher = new RijndaelManaged(); 
        cipher.Mode = CipherMode.CFB;
        cipher.Padding = PaddingMode.None;
        cipher.KeySize = 128;
        cipher.FeedbackSize = 8;
        cipher.Key = key;
        cipher.IV = key;
        return cipher;
    }

    public byte[] Crypt(byte[] buffer, int offset, int count) {
        return enc.TransformFinalBlock(buffer, offset, count); 
    }

C# Test code:

 static void Test() {
        // Init
        var AesCrypto = new AesCrypto(Encoding.UTF8.GetBytes("aaabbbccaaabbbcc"));
        var testData = Encoding.UTF8.GetBytes(createDataSize(9000000)); // 9mb test.

        // Timer
        var stopWatch = new Stopwatch();
        stopWatch.Start();
        AesCrypto.Crypt(testData, 0, testData.Length);
        stopWatch.Stop();
        Console.WriteLine("AesCrypto.Crypt took: " + stopWatch.ElapsedMilliseconds);
 }
 static string createDataSize(int msgSize)
    {
        StringBuilder sb = new StringBuilder(msgSize);
        for (int i = 0; i < msgSize; i++)
        {
            sb.Append('a');
        }
        return sb.ToString();
    }

Result: "AesCrypto.Crypt took: 3626"

JAVA Cipher code:

public Cryptor(boolean reader) throws CryptingException {

    keySpec = new SecretKeySpec(secretKey.getBytes(CHARSET), "AES");
    ivSpec = new IvParameterSpec(iv.getBytes(CHARSET));
    try {
        cipher = Cipher.getInstance("AES/CFB8/NoPadding");
        if (reader) cipher.init(Cipher.DECRYPT_MODE, keySpec, ivSpec);
        else cipher.init(Cipher.ENCRYPT_MODE, keySpec, ivSpec);
    } catch (NoSuchAlgorithmException e) {
        throw new SecurityException(e);
    } catch (NoSuchPaddingException e) {
        throw new SecurityException(e);
    }catch (InvalidKeyException e) {
        throw new SecurityException(e);
    } catch (InvalidAlgorithmParameterException e) {
        throw new SecurityException(e);
    }
}

public byte[] decrypt(byte[] input) throws CryptingException {
        return cipher.update(input);
}

public byte[] encrypt(String input) throws CryptingException {
    return cipher.update(input.getBytes());
}

Java Test code:

private static void Test() {
    // Init
    String data = createDataSize(9392963);
    Cryptor writer = new Cryptor(false);

    // Timer
    Instant starts = Instant.now();
    byte[] encrypted = writer.encrypt(data);
    Instant ends = Instant.now();
    System.out.println("Java Encryption took: " + Duration.between(starts, ends));
}
private static String createDataSize(int msgSize) {
      StringBuilder sb = new StringBuilder(msgSize);
      for (int i=0; i<msgSize; i++) {
        sb.append('a');
      }
      return sb.toString();
}

Result: "Java Encryption took: PT0.469S"

Possible solution:

After researching this quite a bit it seems that AesCryptoServiceProvider() has around the same performance as Java's equivalence and has a mostly identical results. The problem with this is however that it requires padding, whereas Java's equivalence does not require padding. For example this means if I want to encrypt "abcdab" it would only encrypt "abcd" and return the result for that and keep the rest ("ab") internally. If I use padding I can get it to return the full "abcdab" encrypted, however then it has additional data appended and the symmetric algorithm is de-synced, because in java I could encrypt "abcdab" without any padding.

Question

So finally my question is how would could I make the C# encryption/decryption process just as fast as Java's? Am I doing something wrong with AesCryptoServiceProvider, maybe it's possible for it to not require padding?