Quering Spotfire for a folder's childItems takes too long

Our Index page displays a list of the analysis files located in a folder (each user has a folder in the Spotfire's Library). The problem is performance. It takes ~5 seconds to get 50 library items and because that happens in our landing page, the whole page takes too long to load. I am wondering if I am doing anything wrong when querying the server. 

We have a method `GetWorkbooks()` (see below) in our service which is called when the landing page loads. It uses a `WcfClient` which exposes the `LibraryService` so we can query Spotfire. 

public IList<Workbook> GetWorkbooks(string email, bool isBufferFolder = false){

        var targetFolderPath = isBufferFolder ? _sharingBufferFolderPath : _userFolderPath;

        var userFolderId = _spotfireUserDataService._libraryService.Invoke(x => x.pathToId(new pathToId($"{targetFolderPath}/{email}", SpotfireLibraryItemType.Folder))).@return;

        var workBooks = new List<Workbook>();

        // only retrieve workbooks if there is a user folder

        if (userFolderId != null){

            var libraryItems = _spotfireUserDataService._libraryService.Invoke(x => x.getChildItems(new getChildItems(userFolderId))).@return;

            // check if there are any items in the folder, if not return the above empty list

            if (libraryItems != null) {// get all analysis/workbook ('dxp') files for the user

                workBooks = libraryItems

                    .Where(i => i.type == SpotfireLibraryItemType.DXP)

                    .OrderByDescending(j => j.accessed.Date)

                    .Select(x => new Workbook {

                        Name = x.title,

                        Id = x.id,

                        ModifiedDate = x.modified,

                        Metadata = new {

                            SharedBy = x.properties.Where(i => i.key == "SharedBy").FirstOrDefault()?.values[0],

                            SharedDate = new DateTime(Convert.ToInt64(x.properties.Where(i => i.key == "SharedDate").FirstOrDefault()?.values[0]))





        return workBooks;



This is a screenshot of the call:

This is the Spotfire's Library hierarchy:




This is my `WcfClient.cs`:

    public class WcfClient<T> : IDisposable{

        private T _wrappedChannel;

        private static readonly object _channelLock = new object();

        private readonly ChannelFactory<T> _factory;

        private readonly ITokenProvider _tokenProvider;


        public WcfClient(ChannelFactory<T> factory, ITokenProvider tokenProvider){

            _factory = factory;

            _tokenProvider = tokenProvider;



        protected T WrappedChannel {


                lock (_channelLock) {

                    if (!Equals(_wrappedChannel, default(T))){

                        var state = ((ICommunicationObject)_wrappedChannel).State;

                        if (state == CommunicationState.Faulted){

                            _wrappedChannel = default(T);



                    if (Equals(_wrappedChannel, default(T))){

                        _wrappedChannel = _factory.CreateChannel();



                return _wrappedChannel;




        public void Invoke(Action<T> action){




            catch (FaultException){





        public TResult Invoke<TResult>(Func<T, TResult> action){


                return action(WrappedChannel);




Could anyone please provide any tips on how I can improve the performance?