Why PRO SDK SearchTextBox Suggestions Display Slow?

[Amadeus111]

I implemented a PRO SDK SearchTextBox however it works pretty slow. I read from a CSV file and create an object type Observable Collection and dump that into SuggestionSource then filter the results as SearchBox text change. Do you have any idea what I am doing wrong?

XAML :

<!-- Inserting inside user control -->

xmlns:controls="clr-namespace:ArcGIS.Desktop.Framework.Controls;assembly=ArcGIS.Desktop.Framework"

<!-- Inserting inside a stack panel-->

<controls:SearchTextBox x:Name="SearchLayersBox" Height="23" Margin="5,5,10,10" VerticalAlignment="Top" InfoText="Search" SearchMode="Auto" ShowHistory="True" Search="SearchTextBox_Search" Initialized="SearchLayersBox_Initialized" TextChanged="SearchLayersBox_TextChanged" SuggestionListMax="15" />

C# 

public void LayersListSearchBox()
{
    LayerDict.Clear();
    DataListBoxSource.Clear();
    var path = @"\\nrdsmnt6\mine maps\DMP_Database\Layer_Properties_spc_CSV.csv";
    using (TextFieldParser csvParser = new TextFieldParser(path))
    {
       csvParser.SetDelimiters(new string[] { "*%&" });
       csvParser.HasFieldsEnclosedInQuotes = false;
       //Skip the row with the column names
       csvParser.ReadLine();
       while (!csvParser.EndOfData)
          {
             string[] fields = csvParser.ReadFields();
 
             string LayerDisplayName = fields[3].Substring(1);
             SearchSuggestCollection.Add(LayerDisplayName);
          }
    }
 
    SearchLayersBox.SuggestionSource = SearchSuggestCollection;
 }

private void SearchLayersBox_TextChanged(object sender, TextChangedEventArgs e)
{
    string searchString = SearchLayersBox.Text;
    ObservableCollection<object> filteredCollection = new ObservableCollection<object>(from objectL in SearchSuggestCollection where objectL.ToString().Contains(searchString) select objectL);
    SearchLayersBox.SuggestionSource = filteredCollection;
}

private void SearchLayersBox_Initialized(object sender, EventArgs e)
{
   LayersListSearchBox();
}

[Amadeus111 · Accepted solution]

The major problem was assignment of the collection right after initialization and assigning again when it is updated. One assignment was enough as far as it is Observable Collection. 

SearchLayersBox.SuggestionSource = SearchSuggestCollection;

Then I also add a requirement to enter 3 characters before firing up the autosuggestions. However, this is not proper MVVM model. If somebody can explain a proper structure for MVVM model for ArcGIS Pro SDK framework, it would be very useful.