A function to test the download speed of a website.

Test-Speed.ps1

function Test-Speed {
    param(
        [string] $TestUrl
    )
    # Create an HttpClient object
	$client = New-Object System.Net.Http.HttpClient;
    
    # Create a Stopwatch to test the download speed.
    $sw = New-Object System.Diagnostics.Stopwatch;
	
    # Start the Stopwatch, retrieve the URL, and then stop the Stopwatch
    $sw.Start();
	$response = $client.GetAsync($TestUrl).Result;
	$sw.Stop();
    
    # Calculate the speed in Mbit/s (SI Units)
    $downloadSpeedMbps = ($response.Content.Headers.ContentLength * 8.0 / $sw.Elapsed.TotalSeconds) / 1000000.0;
    
    if ($response -eq $null) {
        Write-Error "An unknown error occured while testing $TestUrl";
        return;
    }
    
    $result = [pscustomobject]@{
        IsSuccessfull = $response.IsSuccessStatusCode
        ResponseSize = $response.Content.Headers.ContentLength.ToString("0 bytes")
        Status = $response.ReasonPhrase
        TotalSeconds = $sw.Elapsed.TotalSeconds
        TotalMilliseconds = $sw.Elapsed.TotalMilliseconds
        DownloadSpeed = $downloadSpeedMbps.ToString("0 Mbps")
    };
    
	return $result;
}

Requires PowerShell Core