C#中计算耗时

DateTime ProStartTime = DateTime.Now;

ControlForm.show_info(LCDForm.Rsee_Handle.Rsee_DIST_Run());

DateTime ProEndTime = DateTime.Now;

string ProDuration = (ProEndTime- ProStartTime).ToString("ssfff");
string ProStart = ProStartTime.ToString("yyyy:MM:dd:HH:mm:ss:fff");
string ProEnd = ProEndTime.ToString("yyyy:MM:dd:HH:mm:ss:fff");