procedure TForm1.Test;
const
  Src = 'e:\DelphiTest\A';
  Dst = 'e:\DelphiTest\B\';
begin
  var Closure :=
    procedure (const aFileName: string)
    begin
      TTask.Run(
        procedure
        begin
          var FileContent := TFile.ReadAllBytes(aFileName);
          TFile.WriteAllBytes(Dst + TPath.GetFileName(aFileName), FileContent);
          TFile.Delete(aFileName);
        end
      );
    end;

  var Files := TDirectory.GetFiles(Src);
  for var FileName in Files do
    Closure(FileName);
end;

  var Closure :=
    procedure (const aFileName: string)
    begin
      TTask.Run(
        procedure
        begin
          var FileContent := TFile.ReadAllBytes(aFileName);
          // добавим чтобы нагрузить процессор
          for var ByteContent1 in FileContent do
            for var ByteContent2 in FileContent do
              if Random(10) < 5 then
                Break;

          TFile.WriteAllBytes(Dst + TPath.GetFileName(aFileName), FileContent);
          TFile.Delete(aFileName);
        end
      );
    end;