procedure TForm1.Button1Click(Sender: TObject);
var
  KernelTimeStart, KernelTimeEnd : TFileTime;
  UserTimeStart, UserTimeEnd     : TFileTime;
  TotalProcessorTime             : Cardinal;
  Dummy1, Dummy2                 : TFileTime;
begin
  GetThreadTimes(GetCurrentThread, Dummy1, Dummy2, KernelTimeStart, UserTimeStart);

  DoSomething;

  GetThreadTimes(GetCurrentThread, Dummy1, Dummy2, KernelTimeEnd, UserTimeEnd);
  TotalProcessorTime:=KernelTimeEnd.dwLowDateTime - KernelTimeStart.dwLowDateTime +
                      UserTimeEnd.dwLowDateTime - UserTimeStart.dwLowDateTime;
  ShowMessage(Format('You wasted %.4f sec', [TotalProcessorTime * 1e-7]));
end;

Thread kernel mode and user mode times are amounts of time. For example, if a thread has spent one second in kernel mode, this function will fill the FILETIME structure specified by lpKernelTime with a 64-bit value of ten million. That is the number of 100-nanosecond units in one second.

procedure TForm1.Shellsort(var x: vector; Var  s : Longint; N: Integer);
var
  h, j, i, r, t, m: integer;
  STim, ETim: Longint;
begin
  t := round(ln(n) / ln(2)) - 1;
  STim := GetTickCount;
  Memo1.Lines.Add(IntToStr(STim)); // для контроля считалось или нет
  for m := t downto 1 do
    begin
      h := 0;
      for i := 1 to m do
        h := 2 * h + 1;
      for i := h + 1 to N do
        begin
          r := x[i]; j := i - h;
          while (j >= 1) and (r < x[j]) do
            begin
              x[j + h] := x[j];
              Dec(j, h);
            end;
          x[j + h] := r
        end;
    end;
  ETim := GetTickCount; <-- в переменную ничего не заносится
  Memo1.Lines.Add(IntToStr(ETim)); <-- вылетает здесь, а если убрать да и вообще при компил. след строка игнорируется
  s := ETim - STim;
end;

procedure TForm1.Button1Click(Sender: TObject);
var
  STim, ETim, s: Longint;
begin
  STim := GetTickCount;
  ETim := GetTickCount;
  s := ETim - STim;<-- таже история строка просто игнорируется
end;

ToT>procedure TForm1.Button1Click(Sender: TObject);
ToT>var
ToT>  STim, ETim, s: Longint;
ToT>begin
ToT>  STim := GetTickCount;
ToT>  ETim := GetTickCount;
ToT>  s := ETim - STim;<-- таже история строка просто игнорируется
ToT>end;
ToT>

  ShowMessage(IntToStr(s));

var
  ftKernelTimeStart, ftKernelTimeEnd: FILETIME;
  ftUserTimeStart, ftUserTimeEnd: FILETIME;
  ftDummy: FILETIME;
  qwKernelTimeElapsed, qwUserTimeElapsed, qwTotalTimeElapsed: FILETIME;
begin
  GetThreadTimes(GetCurrentThread, ftDummy, ftDummy, ftKernelTimeStart, ftUserTimeStart);
  ...
 GetThreadTimes(GetCurrentThread, ftDummy, ftDummy, ftKernelTimeEnd, ftUserTimeEnd);

  qwKernelTimeElapsed := ftKernelTimeEnd - ftKernelTimeStart;
  qwUserTimeElapsed := ftUserTimeEnd - ftUserTimeStart;
  qwTotalTimeElapsed = qwKernelTimeElapsed + qwUserTimeElapsed;
end;