I'm trying to create a simple Hex Editor with C#. For this I'm writing the file into an byte-array, which works fine. But as soon as I put out the bytes to a Textbox in form of a string, the overall performance of the program becomes pretty bad. For example a 190kb file takes about 40 seconds, till it is displayed in the textbox. While that the program is not responding.
The function:
void open()
    {
        fullstring = "";
        OpenFileDialog op = new OpenFileDialog();
        op.ShowDialog();
        file = op.FileName;
        byte[] fileB = File.ReadAllBytes(file);
        long b = fileB.Length;
        for (int i = 0; i < fileB.Length; i++)
        {
            fullstring = fullstring + fileB[i].ToString("X") + "  ";
        }
        textBox9.Text = fullstring;
    }
Is there a way to improve performance in this function?
 
     
    