procedure TForm1.DrPixelsClick(Sender: TObject);
var
 X,Y: Integer;
 Start, Finish: Real;
begin
 Start := Time;
 for X := 0 to Form1.Width do
  for Y := 0 to Form1.Height do
   Canvas.Pixels[X,Y] := 255;
 Finish := Time - Start;
 Form1.Caption := FloatToStr(Finish);
end;

procedure TForm1.DrLinesClick(Sender: TObject);
var
 X: Integer;
 Start, Finish: Real;
begin
 Start := Time;
 for X := 0 to Form1.Width do
 begin
  Canvas.MoveTo(X, 0);
  Canvas.LineTo(X, Form1.Height);
 end;
 Finish := Time - Start;
 Form1.Caption := FloatToStr(Finish);
end;