BlazorWebView slow on initial load (n+1 issue with blazor.webview.js::insertElement)

[gentledepp]

Hello!

I was playing around with BlazorWebView lately and I essentially like it a lot.
However, we need to render some quite large UI (essentially a for-each loop that spits out textboxes and checkboxes).

<h1>Show Form</h1>

<p>This component demonstrates rendering our forms in Blazor.</p>

@if (FormViewModel is null)
{
    <p><em>Loading...</em></p>
}
else
{
    <Virtualize Items="@FormViewModel.VisibleFields" Context="viewModel">
        @if (viewModel is TextFieldViewModel tf)
        {
            <MauiBlazorApp3.FormParts.TextBox ViewModel=@tf />
        }
        else if (viewModel is CheckBoxFieldViewModel cbf)
        {
            <MauiBlazorApp3.FormParts.Checkbox ViewModel=@cbf />
        }
        else if (viewModel is FieldGroupViewModel fg)
        {
            <MauiBlazorApp3.FormParts.Headline ViewModel=@fg />
        }
        else if (viewModel is VirtualFieldGroupViewModel vfg)
        {
            <tr><td>@vfg.Title</td><td>X</td></tr>
        }
        else
        {
            <tr><td>@viewModel.HighlightedTitle.FirstOrDefault()</td><td>X</td></tr>
        }
    </Virtualize>
}

We noticed, that the initial load is very slow.
With virtualize enabled, on windows, it takes 2 seconds (in release mode!)
On an android phone, it even takes 10 seconds.

Now, this is no way near the complexity of our final product.

So I dug into blazor a bit to find out whether we are doing something wrong.
After pretty-printing blazor.webview.js, I stumbled over a function "insertElement" which seems to be called for every single element that we render in our blazor page:

To me it seems that this is the bottleneck, so I wonder if this could be enhanced by providing something like a "server-side prerender"

Meaning: For the first load, instead of calling the BlazorWebView for each and every element that it should create in the dom, rather send one pre-rendered html fragment to be rendered.
Once that is done, let blazor continue to gradually update the UI.

Is this something that is on the roadmap and I missed it?
Could this be implemented?
Or am I searching at the wrong spot and we do have to find another way to speed things up dramatically?

Thank you for helping me out!

@bruzkovsky - fyi ;-)