#requires -version 4.0
#requires -runasadministrator

#Retrieving all events with ID 100

$BootEvents = Get-WinEvent -FilterHashtable @{
  logname='Microsoft-Windows-Diagnostics-Performance/Operational';
  id=100}

#Building a boot history with, for each boot, the duration of the boot process

$BootHistory = $BootEvents | Select-Object TimeCreated, LevelDisplayName,
        @{
   n="BootStartTime";
   e={Get-Date -Date (([xml]$_.ToXml()).Event.EventData.Data |
  Where-Object {$_.name -eq "BootStartTime"})."#text"}
  },
        @{
   n="BootEndTime";
   e={Get-Date -Date (([xml]$_.ToXml()).Event.EventData.Data |
  Where-Object {$_.name -eq "BootEndTime"})."#text"}
  },
        @{
   n="MainPathBootTime";
   e={([timespan]::FromMilliseconds((([xml]$_.ToXml()).Event.EventData.Data |
  Where-Object {$_.name -eq "MainPathBootTime"})."#text"))}
  },
 @{
   n="BootPostBootTime";
   e={([timespan]::FromMilliseconds((([xml]$_.ToXml()).Event.EventData.Data |
  Where-Object {$_.name -eq "BootPostBootTime"})."#text"))}
  }

$BootStartTime = $BootHistory.bootstarttime

$MainPathBootTime = $BootHistory.MainPathBootTime

$PostBootTime = $BootHistory.BootPostBootTime

$LastBootDate = $BootStartTime | Select-Object -First 1

$OldestRecordedBoot = $BootStartTime | Select-Object -last 1

$BootFrequencyInDays = ($LastBootDate - $OldestRecordedBoot).days / $BootStartTime.Count

$AvgMainBootDuration = [timespan]::FromSeconds((($MainPathBootTime.totalseconds |
  Measure -A).average)).ToString("hh\:mm\:ss")

$AvgPostBootDuration = [timespan]::FromSeconds((($PostBootTime.totalseconds |
  Measure -A).average)).ToString("hh\:mm\:ss")

$ActualWindowsBootTime = (Get-Date) - `
  ([timespan]::FromMilliseconds([Math]::Abs([Environment]::TickCount)))

$LastEvent12 = Get-WinEvent -FilterHashtable @{
  LogName='System';
  ProviderName='Microsoft-Windows-Kernel-General';
  ID=12} -MaxEvents 1 | Select -ExpandProperty TimeCreated


#Building an object containing a quick summary of your last computer boot, as
#well as of the average boot duration.

$BootInformation = 1 | Select-Object BootFrequencyInDays, AvgMainBootDuration, `
   AvgPostBootDuration, LastBootDate, OldestRecordedBoot, `
   ActualWindowsBootTime, LastEvent12
$BootInformation.BootFrequencyInDays = $BootFrequencyInDays
$BootInformation.AvgMainBootDuration = $AvgMainBootDuration
$BootInformation.AvgPostBootDuration = $AvgPostBootDuration
$BootInformation.LastBootDate = $LastBootDate
$BootInformation.OldestRecordedBoot = $OldestRecordedBoot
$BootInformation.ActualWindowsBootTime = $ActualWindowsBootTime
$BootInformation.LastEvent12 = $LastEvent12

#Grouping boot events by Level, in order to see if your computer boot duration is below or
#beyond the thresholds defined in the Registry
$BootAnalysis = Get-WinEvent -FilterHashtable @{
  logname='Microsoft-Windows-Diagnostics-Performance/Operational';
  id=100} |
  Group-Object LevelDisplayName

$BootHistory | Out-Gridview