unit Unit2;

interface

uses
  System.SysUtils, System.Types, System.UITypes, System.Classes, System.Variants,
  FMX.Types, FMX.Controls, FMX.Forms, FMX.Graphics, FMX.Dialogs, FMX.Controls.Presentation, FMX.StdCtrls;

const
  TestCount = 100000000;
type
  TForm2 = class(TForm)
    Button1: TButton;
    Label1: TLabel;
    Label2: TLabel;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
    FEmptyCount: Integer;
    FStrCount: Integer;
  public
    { Public declarations }
    procedure Test(const S: string);
    procedure TestAsEmptyStr;
    procedure TestLiteral;
  end;

var
  Form2: TForm2;

implementation

{$R *.fmx}

procedure TForm2.Button1Click(Sender: TObject);
var
  T2, T1: TDateTime;
begin
  T2 := Now;
  repeat
    T1 := Now;
  until T1 <> T2;
  TestAsEmptyStr;
  T2 := Now;
  Label1.Text := FormatFloat('0.000', (T2 - T1) * SecsPerDay);

  T2 := Now;
  repeat
    T1 := Now;
  until T1 <> T2;
  TestLiteral;
  T2 := Now;
  Label2.Text := FormatFloat('0.000', (T2 - T1) * SecsPerDay);
end;

procedure TForm2.Test(const S: string);
begin
  if S = EmptyStr then
    Inc(FEmptyCount)
  else
    Inc(FStrCount);
end;

procedure TForm2.TestAsEmptyStr;
var
  S: string;
  I: Integer;
begin
  for I := 0 to TestCount - 1 do
  begin
    S := EmptyStr;
    Test(S);
  end;
end;

procedure TForm2.TestLiteral;
var
  S: string;
  I: Integer;
begin
  for I := 0 to TestCount - 1 do
  begin
    S := '';
    Test(S);
  end;
end;

end.