Tip: You can create a stopwatch in Powershell using the Stopwatch class.
Create and Start
$stopwatch = [System.Diagnostics.Stopwatch]::StartNew()
Stop
$stopwatch.Stop()
Elasped Time
$stopwatch.Elapsed
Reset
$stopwatch.Reset()
Restart
$stopwatch.Restart()
Note: The property Isrunning indicates whether if the stopwatch is running.