MemoryStream eats a big system memory, to evit this, you can use this custom stream made by me instead of MemoryStream.

class CustomStream : Stream
{
    string _T;
    long _pos;
    System.Text.Encoding _encoder = Encoding.Default;

    public CustomStream()
        : this("")
    {
    }

    public byte[] GetBytes()

    {

        return _encoder.GetBytes(_T);

    }

    public CustomStream(string BaseText)
    {
        _T = BaseText;
        _pos = 0;
    }

    public override bool CanRead
    {
        get { return true; }
    }

    public override bool CanSeek
    {
        get { return true; }
    }

    public override bool CanWrite
    {
        get { return true; }
    }

    public override void Flush()
    {
         _T = "";

         _pos = 0;

    }

    public override long Length
    {
        get { return _T.Length; }
    }

    public override long Position
    {
        get
        {
            return _pos;
        }
        set
        {
            _pos = value;
        }
    }

    public override int Read(byte[] buffer, int offset, int count)
    {
        int ret = 0;
        for (int i = 0; i < count; i++)
        {
            if (_T.Length <= _pos)
            {
                break;
            }
            buffer[i] = (byte)_T[(int)_pos];
            _pos++;
            ret++;
        }
        return ret;
    }

    public override long Seek(long offset, SeekOrigin origin)
    {
        if (origin != SeekOrigin.Begin)
        {
            throw new NotImplementedException();
        }
        _pos = offset;
        return _pos;
    }

    public override void SetLength(long value)
    {
        if (_T.Length > value)
        {
            string nstr = "";
            for (int i = 0; i < value; i++)
            {
                nstr += _T[i];
            }
            _T = nstr;
        }
        else if (_T.Length < value)
        {
            for (int i = 0; i < value - _T.Length; i++)
            {
                _T += "\0";
            }
        }
    }

    public override void Write(byte[] buffer, int offset, int count)
    {
        _T += _encoder.GetString(buffer, offset, count);
    }
}

Some fixes in edit since: 30/10 12:43 (GMT-3)