UI Thread slow response due to the populating of 50k records file in ViewModel.Source observable collection

Describe the bug

Dear Friends,

first of I would like to appreciate your framework. It is really amazing tool and realy enjoy it. However I'm facing some wierd spec. effect. I has generated project for DataGrid population with 50 k records from csv file. all works good untill I starting populating ViewModel.Source property this is realy hanging main UI thread. I did moved as much as possible code to the async style but the best i get is slow response UI. Here is how moved my code to the async:

` public async Task<IEnumerable> ProcessCSVData(string csvFilePath, CSVDataService service) {

    Microsoft.UI.Dispatching.DispatcherQueue dispatcherQueue = Microsoft.UI.Dispatching.DispatcherQueue.GetForCurrentThread();

    List<ADUserObject> userObjects = new List<ADUserObject>();

    Source.Clear();

    var enumerator = service.SeedCSVFileDataAsync(csvFilePath);

    Source = new ObservableCollection<ADUserObject>();
    await foreach (var item in enumerator.WithCancellation(CancellationToken.None))
    {
        userObjects.Add(item);
        Source.Add(item);
    }

    return userObjects;
}

What's intersting is that 50k records gets populated in my List for couple of ms, but once I starting use add thouse to the datagrid observable source property Source.Add(item); the things are getting really bad.

I do understand that the root cause are tons of CollectionUpdate events so I tried to cheat and re-populate Source after I get all data red in my collection as follow: Source = new ObservableCollection<ADUserObject>(userObjects); but once i applied this Observable collection stops receiving any events so it end's up empty no matter what you do. I may guess here that the problem is that by the time when I re-initialize Observable collection property it get's hard coded by the comipler in *.g.cs files so it broke some logic somwehre...

I'm really not claim that this is a bug, but If could help me to improve my logick and get main UI thread responsive while it populates 50k lines in Source prop I would be very apprecaite you.

Best regards, Maks.

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Additional context

No response

Applies to the following platforms:

[X] WinUI
[ ] WPF
[ ] UWP

About your setup

Visual Studio Version: 2022 Pro with latest updates:
Template Studio Wizard Version: 5.4
Windows Build: Windows 11 Pro 22H2 OS Build 22621.1778

microsoft / TemplateStudio