Как сделать поиск слова в списке побыстрее?

unit Unit1;
 
interface
 
uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, Gauge;
 
type
  TForm1 = class(TForm)
    Button1: TButton;
    Button2: TButton;
    Button3: TButton;
    OpenDialog1: TOpenDialog;
    OpenDialog2: TOpenDialog;
    Gauge1: TGauge;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure Button3Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;
 
var
  Form1: TForm1;
  S1,S2:Tstringlist;
 
implementation
 
{$R *.dfm}
 
procedure TForm1.Button1Click(Sender: TObject);
begin
s1:=Tstringlist.Create;
s1.Sorted := True;
s1.Duplicates := dupIgnore;
if opendialog1.Execute then
s1.LoadFromFile(opendialog1.FileName);
end;
 
procedure TForm1.Button2Click(Sender: TObject);
begin
s2:=Tstringlist.Create;
s2.Sorted := True;
s2.Duplicates := dupIgnore;
if opendialog2.Execute then
s2.LoadFromFile(opendialog2.FileName);
end;
 
procedure TForm1.Button3Click(Sender: TObject);
var
i,j:integer;
List:Tstringlist;
begin
Gauge1.Progress:=0;
Gauge1.Maxvalue:=s1.count*s2.Count;
List:=Tstringlist.Create;
for i:=0 to s1.Count-1 do
for j:=0 to s2.Count-1 do begin
if pos(s1[i],s2[j])>0 then
List.Add(s2[j]);
Application.ProcessMessages;
Gauge1.Progress := Gauge1.Progress +1;
end;
Showmessage('OK');
List.SaveToFile(extractfilepath(paramstr(0))+'Result.txt');
Freeandnil(List);
end;
 
end.