Timing setTimeout vs Task.Yield in Blazor

setTimeoutTiming.razor

@* https://stackoverflow.com/q/70091469/1768303 *@
@inject IJSRuntime JS

<p>@progress</p>
<p>setTimeout: @result1</p>
<p>Task.Yield: @result2</p>

@code 
{
    string progress = "please wait...";
    string result1 = "?";
    string result2 = "?";

    protected override void OnAfterRender(bool firstRender)
    {
        if (firstRender) RunAsync();
    }

    const string SCRIPT = @"({ 
        test: async n => { 
            for (i = 0; i < n; i++) {
                await new Promise(r => setTimeout(r, 0)); 
            }
        }
    })";

    async void RunAsync() 
    {
        const int iterations = 1000;
        var jsTest = await JS.InvokeAsync<IJSInProcessObjectReference>("eval", SCRIPT); 

        // timeing await new Promise(r => setTimeout(r))
        var sw1 = System.Diagnostics.Stopwatch.StartNew();
        await jsTest.InvokeVoidAsync("test", iterations);
        result1 = $"{sw1.ElapsedMilliseconds}ms";
        StateHasChanged();

        // timing await Task.Yield()
        var sw2 = System.Diagnostics.Stopwatch.StartNew();
        for (int i = 0; i < iterations; i++) 
        {
            //await Yield();
            await Task.Yield();
        }
        result2 = $"{sw2.ElapsedMilliseconds}ms";
        StateHasChanged();

        progress = String.Empty;
        StateHasChanged();
    }

    static Task Yield() 
    {
        var tcs = new TaskCompletionSource<bool>();
        System.Threading.ThreadPool.QueueUserWorkItem(_ => tcs.TrySetResult(true));
        return tcs.Task;
    }
}