如何提高代码执行速度。我在php中使用了一些计算

Question

如何使这个计算更快，速度非常慢。我用不同的方式尝试了很多次，但我做不到。拜托，任何人都可以帮助我。

我使用Ajax和Jquery从用户输入中获取值，并在Ajax.i中使用cakephp2.5将此值返回给用户。一些值来自数据库及其我的控制器代码。所以请帮助更快地制作这段代码。

CryptoStream GetEncryptStream(string filename)
{
    var rjndl = new RijndaelManaged();
    rjndl.KeySize = 256;
    rjndl.BlockSize = 256;
    rjndl.Mode = CipherMode.CBC;
    rjndl.Padding = PaddingMode.PKCS7;

    // Open read stream of unencrypted source fileStream:
    var fileStream = new FileStream(filename, FileMode.Open); 

    /* Get key and iv */

    var transform = rjndl.CreateEncryptor(key, iv);

    // CryptoStream in *read* mode:
    var cryptoStream = new CryptoStream(fileStream, transform, CryptoStreamMode.Read); 

    /* What can I do here to insert the unencrypted IV at the start of the
       stream so that the first X bytes returned by cryptoStream.Read are
       the IV, before the bytes of the encrypted file are returned? */

    return cryptoStream; // Return CryptoStream to be consumed elsewhere
}