gistfile1.ps1

function Get-DownloadSpeed
{
    [CmdletBinding()]
    Param
    (
        # Param1 help description
        [Parameter(Mandatory=$true, Position=0)]
        $SpeedtestServer,

        # Param2 help description
        [Parameter(Mandatory=$true, Position=1)]
        $DownLoad
    )

    Process
    {
        [string]$testurl = $SpeedtestServer + $DownLoad
        try {
            $Error = $null
            $time = measure-command {$dl = Invoke-WebRequest -uri $testurl -TimeoutSec 1}
        } catch {
            write-host "Error downloading $testurl "
            write-host $dl
            break
        }
        $result = $($dl.RawContentLength) / $($time.totalseconds)
        $resultmb = $result / 1000000
        $resultmb = [math]::Round($resultmb,2) #round to 2 decimal places
        $dlmb = $($dl.RawContentLength) / 1000000
        $dlmb = [math]::Round($dlmb,2)
        $secs = $($time.totalseconds)
        $secs = [math]::Round($secs,2)
        Write-host "$testurl downloaded $dlmb Mbit in $secs seconds at $resultmb Mbit/s"

    }
}

$dl500 = "/speedtest/random500x500.jpg" 
$dl1000 = "/speedtest/random1000x1000.jpg" 
$dl2000 = "/speedtest/random2000x2000.jpg"

$testserver = "www.irongoat.net/speedtest"
#Get-DownloadSpeed $testserver $dl500 
#Get-DownloadSpeed $testserver $dl1000 
Get-DownloadSpeed $testserver $dl2000

A typical response:

www.irongoat.net/speedtest/speedtest/random2000x2000.jpg downloaded 7.91 Mbit in 2.51 seconds at 3.15 Mbit/s

Using the speedtest.net web interface pointed at this same server, 70Mbit/sec results are common. Never as low as 3Mbit/sec