In this Speed Comparison I am reporting on the number of each ESX version I have in my environment to generate a report like the one below.

This table is not really a good example of a standardised environment I admit. However this is the reality of the real world large enterprise.

These timing tests were run against a vCenter with  three (3) clusters of eight (8) hosts.

Old Way

#Get list of all the esx hosts
$vmhostlist = Get-VMHost
#Create ESXi Version count report
$esxiversions = $vmhostlist | ? { $_.Extensiondata.Config.Product.ProductLineId -eq "embeddedEsx" } | Select Name, Version, Build | Group Build | Select Count, @{Name="Version"; Expression={$_.Group[0].Version} }, @{Name="Build"; Expression={$_.Name} }  | Sort-Object Build -Descending

Timings

Task          : Seconds
$vmhostlist   :   6.3
$esxiversions :  35.4

New Way

#Define variable script blocks for Select-Object
$esxtype = @{Name="ESX"; Expression={$_.Config.Product.ProductLineId} }
$version = @{Name="Version"; Expression={$_.Config.Product.Version} }
$build = @{Name="Build"; Expression={$_.Config.Product.Build} }

#Get list of all the esx hosts
$vmhostlist = Get-View -ViewType HostSystem -Property Name, Config.Product.ProductLineId, Config.Product.Version, Config.Product.Build -Filter @{"Config.Product.ProductLineId"="embeddedEsx"}

#Create ESXi Version count report
$esxiversions = $vmhostlist | Select Name, $esxtype, $version, $build | Group Build | Select Count, @{Name="Version"; Expression={$_.Group[0].Version} }, @{Name="Build"; Expression={$_.Name} }  | Sort-Object Version -Descending

Timings

Task          : Seconds
$vmhostlist   :   3.7
$esxiversions :   0.008

Production Results

These are the core components of a reporting script that runs against my entire environment. 950+ ESXi Hosts. Using the old way this report takes 16.5 minutes. Using the new way 27 seconds.

Whilst this approach does make the script a little more convoluted, it clearly demonstrates the power of refining your search criteria to just the information required.