Calculating the speed of routines?

Question

What would be the best and most accurate way to determine how long it took to process a routine, such as a procedure of function?

I ask because I am currently trying

Answer 1

From my knowledge, the most accurate method is by using QueryPerformanceFrequency:

code:

var
  Freq, StartCount, StopCount: Int64;
  TimingSeconds: real;
begin
  QueryPerformanceFrequency(Freq);
  QueryPerformanceCounter(StartCount);
  // Execute process that you want to time: ...
  QueryPerformanceCounter(StopCount);
  TimingSeconds := (StopCount - StartCount) / Freq;
  // Display timing: ... 
end;