Dynamic

The -Update block runs in a dedicated background runspace. When it produces a snapshot, the -View block turns that snapshot into ordinary slide widgets on the presentation thread.

New-Slide 'Clock' {
    New-SlideDynamic -Interval ([TimeSpan]::FromSeconds(2)) -Update {
        Get-Date
    } -View {
        param($snapshot)
        New-SlideText "Updated at $($snapshot.ToString('HH:mm:ss'))"
    }
}

Keep updates self-contained: their runspace does not inherit variables from the deck. Neither block runs during every repaint.