(C#.net) Optimiser une méthode avec des threads

private static Dispatcher dGui = Dispatcher.CurrentDispatcher;

        public static void Compress(string pathNotCompress, string pathCompress, Action<bool, string> Finish, bool highCompress = false)
        {
            if (!File.Exists(pathNotCompress)) { throw new FileNotFoundException(pathNotCompress + " is not found !"); }

            Exception ex = null;
            Thread tCompress = new Thread(new ThreadStart(() =>
            {
                try
                {
                    FileStream sFileNotCompress = new FileStream(pathNotCompress, FileMode.Open, FileAccess.Read);
                    FileStream sFileCompress = new FileStream(pathCompress, FileMode.Create);

                    Compress(sFileCompress, sFileNotCompress, highCompress);

                    sFileCompress.Close();
                    sFileNotCompress.Close();
                } catch (Exception e) { ex = e; }
            }));
            Thread tFinish = new Thread(new ThreadStart(() =>
            {
                tCompress.Start();
                tCompress.Join();

                dGui.Invoke(() => { Finish(ex == null ? false : true, ex == null ? "" : ex.ToString()); });
            }));
            tFinish.Start();
        }

public static async Task Compress(string pathNotCompress, string pathCompress, Action<bool, string> Finish, bool highCompress = false)
        {
            if (!File.Exists(pathNotCompress)) { throw new FileNotFoundException(pathNotCompress + " is not found !"); }
            await Task.Factory.StartNew(()=>{
                    using(FileStream sFileNotCompress = new FileStream(pathNotCompress, FileMode.Open, FileAccess.Read)){
                    using(FileStream sFileCompress = new FileStream(pathCompress, FileMode.Create)){
                    Compress(sFileCompress, sFileNotCompress, highCompress);
            }}});
        }