C#

starttime = DateTime.Now;
reader = new System.IO.StreamReader(openfiledlg.FileName);
char [] text = reader.ReadToEnd().ToCharArray();
reader.Close();
difference = DateTime.Now - starttime;
lbl_result.Text = "File read: " + difference.TotalMilliseconds + " milliseconds.";
lbl_result.Refresh();
pb_conversion.Maximum = text.Length;
//Starting from 1 will gain me 1 character less to analyze.
//don't update the progress bar every iteration.
int i2 = 0;
for(int i = 1; i < text.Length; i+=2){
    text[i] = char.ToUpper(text[i]);
    if(++i2 == 1000){
        i2 = 0;
        pb_conversion.Value = i;
    }                                           //end if
}                                               //end for
difference = DateTime.Now - starttime;
lbl_result.Text = "conversion: " + difference.TotalMilliseconds + " milliseconds.";
lbl_result.Refresh();
pb_conversion.Value = pb_conversion.Maximum;
txtbox_result.SuspendLayout();
txtbox_result.Text = new string(text);
txtbox_result.ResumeLayout();
difference = DateTime.Now - starttime;
lbl_result.Text = "Done in: " + difference.TotalMilliseconds + " milliseconds.";