SubtitleEdit: RecalculateDisplayTime (Optimized)

 public void RecalculateDisplayTime(double maxCharactersPerSecond, int index, double optimalCharactersPerSeconds)
        {
            Paragraph p = GetParagraphOrDefault(index);
            if (p == null)
            {
                return;
            }

            double displayChars = p.Text.CountCharacters(Configuration.Settings.General.CharactersPerSecondsIgnoreWhiteSpace);
            double optimalCharsPerSec = Math.Min(displayChars / Utilities.GetOptimalDisplayMilliseconds(p.Text, optimalCharactersPerSeconds) / TimeCode.BaseUnit, maxCharactersPerSecond);
            double optimalDuratoinInSec = displayChars / optimalCharsPerSec;

            p.EndTime.TotalMilliseconds = p.StartTime.TotalMilliseconds + optimalDuratoinInSec * TimeCode.BaseUnit;

            Paragraph next = GetParagraphOrDefault(index + 1);
            // p is last paragraph or next is null
            if (next == null)
            {
                return;
            }

            double optimalEndTime = next.StartTime.TotalMilliseconds - Configuration.Settings.General.MinimumMillisecondsBetweenLines;
            if (optimalEndTime < p.EndTime.TotalMilliseconds)
            {
                p.EndTime.TotalMilliseconds = Math.Max(p.StartTime.TotalMilliseconds + 1, optimalEndTime);
            }
        }