PowerShell 5.0 Module Loading Bug

ReadMe.md

We've tripped on a bug in PowerShell 5.0 (which seems to be fixed in 5.1) which causes RequiredModules to be extremely slow. This module, which has 11 dependencies, takes a minute to load on my Azure DS1_V2 instance when using RequiredModules, but takes only 6 seconds when removing the RequiredModules and substituting an Import-Module in a psm1 (previously we had no psm1, because this is a pure meta module for install/import purposes).

Module.psd1

@{
    ModuleVersion = '16.12.1.1'

    # QMODHelper is a meta module that exists to depend upon all the Questionmark modules, but ...
	  # RequiredModules are limited/broken in PS 5.x so we work around it by importing in a RootModule
    RootModule = 'Module.psm1'
    RequiredModules = @()
    <#
    RequiredModules = @(
      # Microsoft modules which are required (at least the first two are required just to parse the module files)
      'Microsoft.PowerShell.Utility'    # Set-Alias, Add-Type
      'Microsoft.PowerShell.Management' # Out-String
      'Microsoft.PowerShell.Security'   # Get-Credential

      # Third party dependencies
      'PSCX'
      'PowerShellLogging'
      'Posh-SSH'

      # The new Questionmark modules, in order
      'Questionmark.Assemblies'
      'Questionmark.Database'
      'Questionmark.Configuration'

      # The legacy module.
      'Questionmark.Legacy'
      # Modules which currently depend on the Legacy module
      'Questionmark.Tenant'
    )
    #>
    # ID used to uniquely identify this module
    GUID = '9e121d54-7e76-472c-9133-6adfa3ea37cd'
    Description = 'The Questionmark OnDemand Deployment helper meta-module depends on all the Questionmark modules as a way of installing and loading them all at once'

    # Common stuff for all our modules:
    CompanyName = 'Questionmark Computing Limited'
    Author = 'Joel Bennett'
    Copyright = 'Copyright 2016 Questionmark Computing Limited'

    # Minimum version of the Windows PowerShell engine required by this module
    PowerShellVersion = '5.0'
    # Minimum version of the .NET Framework required by this module
    DotNetFrameworkVersion = '4.0'
    # Minimum version of the common language runtime (CLR) required by this module
    CLRVersion = '4.0.30319'
}

Module.psm1

Import-Module -Global -ErrorAction Stop @(
	# Microsoft modules which are required (at least the first two are required just to parse the module files)
	'Microsoft.PowerShell.Utility'    # Set-Alias, Add-Type
	'Microsoft.PowerShell.Management' # Out-String
	'Microsoft.PowerShell.Security'   # Get-Credential

	# Third party dependencies
	'PSCX'
	'PowerShellLogging'
	'Posh-SSH'

	# The new Questionmark modules, in order
	'Questionmark.Assemblies'
	'Questionmark.Database'
	'Questionmark.Configuration'

	# The legacy module.
	'Questionmark.Legacy'
	# Modules which currently depend on the Legacy module
	'Questionmark.Tenant'
)