Powershell WPF app with timer is a resource hog - wpf

Question

I have been playing with some WPF in PowerShell, with the goal of creating a messaging system and a resizable, scrollable log viewer.
I have the basics of a messaging system working here.
Add-Type -AssemblyName PresentationFramework
Add-Type -AssemblyName System.Windows.Forms
Add-Type -AssemblyName System.Drawing
$icon = [System.Drawing.Icon]::ExtractAssociatedIcon("$pshome\powershell.exe")
[xml]$xaml = '<Window
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Name="window" WindowStyle="None" Height="200" Width="400"
ResizeMode="NoResize" ShowInTaskbar="False">
<Grid Name="grid" Background="#313130" Height="200" Width="400">
<Label Name="label" Content="Messenger Test" Foreground="White" FontSize="18" Margin="10,10,0,15"/>
<TextBox x:Name="Message" Height = "50" FontSize="18" Margin="10,10,0,15" />
</Grid>
</Window>'
$window = [Windows.Markup.XamlReader]::Load([System.Xml.XmlNodeReader]::New($xaml))
$window.Left = [System.Windows.SystemParameters]::WorkArea.Width-$window.Width
$window.Top = 0
$window.Topmost = $true
$message = $Window.FindName('Message')
$timer = [System.Windows.Forms.Timer]::new()
$timer.Add_Tick({
$timer.Stop()
})
# Close the window if it's double clicked
$window.Add_MouseDoubleClick({
$timer.Stop()
})
$maxLoops = 5
for ($messageCount = 1; $messageCount -le $maxLoops; $messageCount++) {
$messageString = "($messageCount) $(Get-Date -format 'HH:mm:ss')"
$message.Text = $messageString
$window.Show()
# start the timer to fire after 10 seconds and then disable itself
$timer.Stop()
$timer.Interval = 5000
$timer.Start()
# while the Tick event did not occur, respond to other events
# such as mouse double-click on the window
while ($timer.Enabled) { [System.Windows.Forms.Application]::DoEvents() }
# the timer tick event happened or the user double-clicked the window
$window.Hide()
# end of the loop reached, no use waiting some more..?
if ($messageCount -ge $maxLoops) {
break
}
# start the timer to fire after (random) 1 - 5 seconds
$interval = (Get-Random -Minimum 1 -Maximum 5)
$timer.Stop()
$timer.Interval = $interval * 10000
$timer.Start()
while ($timer.Enabled) { [System.Windows.Forms.Application]::DoEvents() }
}
$timer.Dispose()
$window.Close()
However, this code will cause a single core to go to 100% utilization. Which doesn't make sense to me. I thought the timer was supposed to be super light weight from a resource utilization standpoint, and that I would get near 0% CPU utilization, with tiny spikes as messages where added. Is there something I am missing here? And in fact, is it really the timer that is the issue, or is there a performance issue with WPF, either in general or in how I have implemented this?
The idea is to have the messaging system run as a service (either a real service, or as a scheduled task that restarts itself) and it would monitor for incoming messages. The messages are added to a queue in the registry, so I could likely use an event rather than a timer. But still, it seems (to me) like this code SHOULDN'T be such a resource hog, and I will learn something useful if I understand why it IS a resource hog.