每秒创建一个新字符串 - 使用String.Format或StringBuilder？

So I have this class:

所以我有这个课:

public class ElapsedTime: BaseObservableObject
{
    public static event PropertyChangedEventHandler StaticPropertyChanged;
    private static Stopwatch _stopWatch;
    private static string _value;

    public static Stopwatch StopWatch
    {
        get { return _stopWatch; }
        set
        {
            _stopWatch = value;
        }
    }

    public static string Value
    {
        get { return _value; }
        set
        {
            _value = value;
            OnStaticPropertyChanged("Value");
        }
    }

    private static void OnStaticPropertyChanged(string propertyName)
    {
        StaticPropertyChanged?.Invoke(null, new PropertyChangedEventArgs(propertyName));
    }
}
public class