最適なパフォーマンスを得るために JQuery で AJAX リクエストを順次実行するにはどうすればよいですか?

(function($) {

  // Create an empty object as the AJAX request queue
  var ajaxQueue = $({});

  $.ajaxQueue = function(ajaxOpts) {
    // Define the deferred object and its promise
    var dfd = $.Deferred(),
        promise = dfd.promise();

    // Enqueue the AJAX request
    ajaxQueue.queue(doRequest);

    // Add an abort method to the promise
    promise.abort = function(statusText) {
      // Abort the request if active
      if (jqXHR) {
        return jqXHR.abort(statusText);
      }

      // Remove the request from the queue
      var queue = ajaxQueue.queue(),
          index = $.inArray(doRequest, queue);
      if (index > -1) {
        queue.splice(index, 1);
      }

      // Reject the deferred
      dfd.rejectWith(ajaxOpts.context || ajaxOpts,
        [promise, statusText, ""]);

      return promise;
    };

    // Define the function to execute the request
    function doRequest(next) {
      jqXHR = $.ajax(ajaxOpts)
        .done(dfd.resolve)
        .fail(dfd.reject)
        .then(next, next);
    }

    return promise;
  };

})(jQuery);

(function($) {
  // Create an empty object as the AJAX request queue
  var ajaxQueue = $({});

  $.ajaxQueue = function(ajaxOpts) {
    // Hold the original complete function
    var oldComplete = ajaxOpts.complete;

    // Enqueue the AJAX request
    ajaxQueue.queue(function(next) {
      // Define a complete callback to proceed with the queue
      ajaxOpts.complete = function() {
        // Execute the original complete function, if present
        if (oldComplete) oldComplete.apply(this, arguments);

        next(); // Proceed to the next request
      };

      // Execute the request
      $.ajax(ajaxOpts);
    });
  };

})(jQuery);