Serialize data using Protobuf-Net in asp.net

Question

I am new to web applications and to be hones I am trying to update an old web-application, trying to speed it up. I analyze the application and see what's the reason of the slow in loading pages.. Of course it's the http-requests and I tried to read how can I speed up the requests and I found that I should serialize the data but I don't know how to do that in my application. So I need someone to tell me how to use serialization or how can I speed up the request please: first it uses angular-js so the request is like that:

viewModelHelper.apiPost('Book/book_getList', null,
                function (result) {
                    $scope.gridOptions.data = result.data;
                });

and I use simillar methods to have the data...

The viewModelHelper.apiPost in the app.js:

self.apiPost = function (uri, data, success, failure, always) {
            self.modelIsValid = true;
            $http.post(MyApp.rootPath + uri, data)
                .then(function (result) {
                    success(result);
                    if (always != null)
                        always();
                }, function (result) {
                    if (failure != null) {
                        failure(result);

                    }
                    else {
                        var errorMessage = result.status + ':' + result.statusText;
                        if (result.data != null) {
                            if (result.data.Message != null)
                                errorMessage += ' - ' + result.data.Message;
                            if (result.data.ExceptionMessage != null)
                                errorMessage += ' - ' + result.data.ExceptionMessage;
                        }

                    }
                    if (always != null)
                        always();
                });
        }

And then let's say in the bookController there is book_getList method:

public JsonResult book_getList()
        {
            List<BookModels> List = obj.book_getList();
            return Json(List, JsonRequestBehavior.AllowGet);
        }

And the bookModels have properties like this:

 public Guid guid_book_id { get; set; }
         public string code { get; set; }
         public string closet { get; set; }
         public string shelf { get; set; }
      public string title { get; set; }

And the method get_list:

public List<BookModels> book_getList()
        {
            try
            {
                OpenCon();
                List<BookModels> List = con.Query<BookModels>("book_getList", param: null, commandType: CommandType.StoredProcedure).ToList();
                return List.ToList();
            }
            catch (Exception)
            {
                throw;
            }
            finally
            {
                CloseCon();
            }
        }

Thanks