Рассчитать время обработки

System.Diagnostics.Stopwatch

Stopwatch sw = new Stopwatch();
sw.Start();
CopyFile();
sw.Stop();
Console.WriteLine("Elapsed : {0}", sw.Elapsed)

Этот класс недоступен в .NET 1.1, вместо этого вы можете использовать QueryPerformanceCounter и API QueryPerformanceFrequency

[DllImport("kernel32.dll", SetLastError=true)]
public static extern bool QueryPerformanceCounter(out long lpPerformanceCount);

[DllImport("kernel32.dll", SetLastError=true)]
public static extern bool QueryPerformanceFrequency(out long lpFrequency);

...

long start;
long end;
long freq;
QueryPerformanceCounter(out start);
CopyFile();
QueryPerformanceCounter(out end);
QueryPerformanceFrequency(out freq);
double seconds = (double)(end - start) / freq;
Console.WriteLine("Elapsed : {0} seconds", seconds)