Defer GUI runspace pool startup

functions/private/Close-WinUtilRunspacePool.ps1

@@ -0,0 +1,18 @@
+function Close-WinUtilRunspacePool {
+    if ($null -eq $sync -or -not $sync.ContainsKey("runspace") -or $null -eq $sync.runspace) {
+        return
+    }
+
+    try {
+        if ($sync.runspace.RunspacePoolStateInfo.State -notin @(
+            [System.Management.Automation.Runspaces.RunspacePoolState]::Closed,
+            [System.Management.Automation.Runspaces.RunspacePoolState]::Closing,
+            [System.Management.Automation.Runspaces.RunspacePoolState]::Broken
+        )) {
+            $sync.runspace.Close()
+        }
+    } finally {
+        $sync.runspace.Dispose()
+        $sync.Remove("runspace")
+    }
+}

functions/private/Initialize-WinUtilRunspacePool.ps1

@@ -0,0 +1,39 @@
+function Initialize-WinUtilRunspacePool {
+    if ($sync.runspace -and $sync.runspace.RunspacePoolStateInfo.State -eq [System.Management.Automation.Runspaces.RunspacePoolState]::Opened) {
+        return $sync.runspace
+    }
+
+    if ($sync.runspace) {
+        Close-WinUtilRunspacePool
+    }
+
+    # Set the maximum number of threads for the RunspacePool to the number of threads on the machine.
+    $maxthreads = [Math]::Max([int]$env:NUMBER_OF_PROCESSORS, 1)
+
+    # Create a new session state for parsing variables into our runspace.
+    $hashVars = New-Object System.Management.Automation.Runspaces.SessionStateVariableEntry -ArgumentList 'sync', $sync, $null
+    $offlineVar = New-Object System.Management.Automation.Runspaces.SessionStateVariableEntry -ArgumentList 'PARAM_OFFLINE', $PARAM_OFFLINE, $null
+    $initialSessionState = [System.Management.Automation.Runspaces.InitialSessionState]::CreateDefault()
+
+    $initialSessionState.Variables.Add($hashVars)
+    $initialSessionState.Variables.Add($offlineVar)
+
+    # Get every WinUtil/WPF function and add it to the session state.
+    $functions = Get-ChildItem function:\ | Where-Object { $_.Name -imatch 'winutil|WPF' }
+    foreach ($function in $functions) {
+        $functionDefinition = Get-Content function:\$($function.Name)
+        $functionEntry = New-Object System.Management.Automation.Runspaces.SessionStateFunctionEntry -ArgumentList $function.Name, $functionDefinition
+        $initialSessionState.Commands.Add($functionEntry)
+    }
+
+    $sync.runspace = [runspacefactory]::CreateRunspacePool(
+        1,                      # Minimum thread count
+        $maxthreads,            # Maximum thread count
+        $initialSessionState,   # Initial session state
+        $Host                   # Machine to create runspaces on
+    )
+
+    $sync.runspace.Open()
+    Write-WinUtilPerformanceCheckpoint -Name "Runspace pool initialized"
+    return $sync.runspace
+}

functions/public/Invoke-WPFRunspace.ps1

@@ -67,6 +67,8 @@ public static class WinUtilRunspaceCleanup
 "@
     }
 
+    Initialize-WinUtilRunspacePool | Out-Null
+
     # Create a PowerShell instance
     $powershell = [powershell]::Create()
 

pester/performance.Tests.ps1

@@ -70,7 +70,8 @@ Describe "Startup performance checkpoints" {
     It "adds runtime checkpoints for startup hotspots" {
         $mainScript = Get-Content -Path (Join-Path $script:repoRoot "scripts\main.ps1") -Raw
         $lazyTabScript = Get-Content -Path (Join-Path $script:repoRoot "functions\private\Initialize-WinUtilTabContent.ps1") -Raw
-        $startupText = "$mainScript`n$lazyTabScript"
+        $runspaceScript = Get-Content -Path (Join-Path $script:repoRoot "functions\private\Initialize-WinUtilRunspacePool.ps1") -Raw
+        $startupText = "$mainScript`n$lazyTabScript`n$runspaceScript"
 
         foreach ($checkpoint in @(
             "Runspace pool initialized",

pester/runspace-lifecycle.Tests.ps1

@@ -0,0 +1,70 @@
+#===========================================================================
+# Tests - Runspace lifecycle
+#===========================================================================
+
+BeforeAll {
+    $script:repoRoot = (Resolve-Path (Join-Path $PSScriptRoot "..")).Path
+    . (Join-Path $script:repoRoot "functions\private\Close-WinUtilRunspacePool.ps1")
+    . (Join-Path $script:repoRoot "functions\private\Initialize-WinUtilRunspacePool.ps1")
+}
+
+Describe "Initialize-WinUtilRunspacePool" {
+    BeforeEach {
+        $script:sync = [Hashtable]::Synchronized(@{})
+        $script:PARAM_OFFLINE = $false
+
+        function Write-WinUtilPerformanceCheckpoint { param($Name) }
+        Mock Write-WinUtilPerformanceCheckpoint { }
+    }
+
+    AfterEach {
+        Close-WinUtilRunspacePool
+        Remove-Variable -Name sync -Scope Script -ErrorAction SilentlyContinue
+        Remove-Variable -Name PARAM_OFFLINE -Scope Script -ErrorAction SilentlyContinue
+    }
+
+    It "creates and reuses one open runspace pool" {
+        $firstPool = Initialize-WinUtilRunspacePool
+        $secondPool = Initialize-WinUtilRunspacePool
+
+        $firstPool.RunspacePoolStateInfo.State | Should -Be ([System.Management.Automation.Runspaces.RunspacePoolState]::Opened)
+        [object]::ReferenceEquals($firstPool, $secondPool) | Should -BeTrue
+        Should -Invoke -CommandName Write-WinUtilPerformanceCheckpoint -Times 1 -Exactly -ParameterFilter {
+            $Name -eq "Runspace pool initialized"
+        }
+    }
+
+    It "closes and removes the active runspace pool" {
+        $pool = Initialize-WinUtilRunspacePool
+
+        Close-WinUtilRunspacePool
+
+        $pool.RunspacePoolStateInfo.State | Should -Be ([System.Management.Automation.Runspaces.RunspacePoolState]::Closed)
+        $script:sync.ContainsKey("runspace") | Should -BeFalse
+    }
+}
+
+Describe "Runspace startup wiring" {
+    It "does not create the GUI runspace pool before automation checks" {
+        $mainScript = Get-Content -Path (Join-Path $script:repoRoot "scripts\main.ps1") -Raw
+        $beforePreset = $mainScript.Substring(0, $mainScript.IndexOf('if ($Preset)'))
+
+        $beforePreset | Should -Not -Match '\[runspacefactory\]::CreateRunspacePool'
+        $beforePreset | Should -Not -Match '\$sync\.runspace\.Open\(\)'
+    }
+
+    It "initializes runspaces synchronously for automation paths and after first render for GUI" {
+        $mainScript = Get-Content -Path (Join-Path $script:repoRoot "scripts\main.ps1") -Raw
+
+        $mainScript | Should -Match 'if \(\$Preset\) \{\s+Initialize-WinUtilRunspacePool'
+        $mainScript | Should -Match 'if \(\$Config\) \{\s+Initialize-WinUtilRunspacePool'
+        $mainScript | Should -Match 'Dispatcher\.BeginInvoke\(\[System\.Windows\.Threading\.DispatcherPriority\]::Background, \[action\]\{ Initialize-WinUtilRunspacePool'
+        $mainScript | Should -Match 'Close-WinUtilRunspacePool'
+    }
+
+    It "creates runspaces on demand before queueing background work" {
+        $runspaceScript = Get-Content -Path (Join-Path $script:repoRoot "functions\public\Invoke-WPFRunspace.ps1") -Raw
+
+        $runspaceScript | Should -Match 'Initialize-WinUtilRunspacePool \| Out-Null'
+    }
+}

pester/runspace.Tests.ps1

@@ -4,6 +4,8 @@
 
 BeforeAll {
     $script:repoRoot = (Resolve-Path (Join-Path $PSScriptRoot "..")).Path
+    . (Join-Path $script:repoRoot "functions\private\Close-WinUtilRunspacePool.ps1")
+    . (Join-Path $script:repoRoot "functions\private\Initialize-WinUtilRunspacePool.ps1")
     . (Join-Path $script:repoRoot "functions\public\Invoke-WPFRunspace.ps1")
     . (Join-Path $script:repoRoot "functions\public\Invoke-WPFFeatureInstall.ps1")
     . (Join-Path $script:repoRoot "functions\public\Invoke-WPFAppxRemoval.ps1")
@@ -18,6 +20,8 @@ BeforeAll {
         $initialSessionState.Variables.Add($syncVariable)
         $script:sync.runspace = [runspacefactory]::CreateRunspacePool(1, 2, $initialSessionState, $Host)
         $script:sync.runspace.Open()
+
+        function Write-WinUtilPerformanceCheckpoint { param($Name) }
     }
 
     function script:Clear-WinUtilRunspaceTestContext {

pester/sanity.Tests.ps1

@@ -206,6 +206,10 @@ Describe "Compiled WinUtil sanity" {
 Describe "Runspace sanity" {
     BeforeAll {
         . (Join-Path $script:repoRoot "functions\public\Invoke-WPFRunspace.ps1")
+        . (Join-Path $script:repoRoot "functions\private\Close-WinUtilRunspacePool.ps1")
+        . (Join-Path $script:repoRoot "functions\private\Initialize-WinUtilRunspacePool.ps1")
+
+        function Write-WinUtilPerformanceCheckpoint { param($Name) }
     }
 
     It "returns a single async handle and runs a scriptblock with arguments in the shared runspace pool" {

pester/xaml.Tests.ps1

@@ -295,6 +295,7 @@ Describe "XAML and sync wiring" {
             "keys",
             "ContainsKey",
             "GetEnumerator",
+            "Remove",
             "logorender",
             "checkmarkrender",
             "warningrender",

scripts/main.ps1

@@ -29,40 +29,6 @@ public enum PackageManagers
 }
 "@
 
-# SPDX-License-Identifier: MIT
-# Set the maximum number of threads for the RunspacePool to the number of threads on the machine
-$maxthreads = [int]$env:NUMBER_OF_PROCESSORS
-
-# Create a new session state for parsing variables into our runspace
-$hashVars = New-object System.Management.Automation.Runspaces.SessionStateVariableEntry -ArgumentList 'sync',$sync,$Null
-$offlineVar = New-object System.Management.Automation.Runspaces.SessionStateVariableEntry -ArgumentList 'PARAM_OFFLINE',$PARAM_OFFLINE,$Null
-$InitialSessionState = [System.Management.Automation.Runspaces.InitialSessionState]::CreateDefault()
-
-# Add the variable to the session state
-$InitialSessionState.Variables.Add($hashVars)
-$InitialSessionState.Variables.Add($offlineVar)
-
-# Get every private function and add them to the session state
-$functions = Get-ChildItem function:\ | Where-Object { $_.Name -imatch 'winutil|WPF' }
-foreach ($function in $functions) {
-    $functionDefinition = Get-Content function:\$($function.name)
-    $functionEntry = New-Object System.Management.Automation.Runspaces.SessionStateFunctionEntry -ArgumentList $($function.name), $functionDefinition
-
-    $initialSessionState.Commands.Add($functionEntry)
-}
-
-# Create the runspace pool
-$sync.runspace = [runspacefactory]::CreateRunspacePool(
-    1,                      # Minimum thread count
-    $maxthreads,            # Maximum thread count
-    $InitialSessionState,   # Initial session state
-    $Host                   # Machine to create runspaces on
-)
-
-# Open the RunspacePool instance
-$sync.runspace.Open()
-Write-WinUtilPerformanceCheckpoint -Name "Runspace pool initialized"
-
 # Create classes for different exceptions
 
 class WingetFailedInstall : Exception {
@@ -97,6 +63,8 @@ Set-Preferences
 Write-WinUtilPerformanceCheckpoint -Name "Preferences loaded"
 
 if ($Preset) {
+    Initialize-WinUtilRunspacePool | Out-Null
+
     # Selects the tweaks from $Preset varible
     Update-WinUtilSelections -flatJson $sync.configs.preset.$Preset
 
@@ -104,21 +72,21 @@ if ($Preset) {
     Invoke-WinUtilAutoRun
 
     # Cleanup and exit
-    $sync.runspace.Dispose()
-    $sync.runspace.Close()
+    Close-WinUtilRunspacePool
     [System.GC]::Collect()
     Stop-Transcript
     return
 }
 
 if ($Config) {
+    Initialize-WinUtilRunspacePool | Out-Null
+
     Invoke-WPFImpex -type "import" -Config $Config
 
     Invoke-WinUtilAutoRun
 
     # Cleanup and exit
-    $sync.runspace.Dispose()
-    $sync.runspace.Close()
+    Close-WinUtilRunspacePool
     [System.GC]::Collect()
     Stop-Transcript
     return
@@ -148,8 +116,7 @@ try {
 if (-NOT ($readerOperationSuccessful)) {
     Write-Host "Failed to parse xaml content using Windows.Markup.XamlReader's Load Method." -ForegroundColor Red
     Write-Host "Quitting WinUtil..." -ForegroundColor Red
-    $sync.runspace.Dispose()
-    $sync.runspace.Close()
+    Close-WinUtilRunspacePool
     [System.GC]::Collect()
     exit 1
 }
@@ -255,8 +222,7 @@ $sync["Form"].title = $sync["Form"].title + " " + $sync.version
 # Set the commands that will run when the form is closed
 $sync["Form"].Add_Closing({
     Stop-WinUtilPerformanceTrace -Name "Window closing"
-    $sync.runspace.Dispose()
-    $sync.runspace.Close()
+    Close-WinUtilRunspacePool
     [System.GC]::Collect()
 })
 
@@ -373,6 +339,7 @@ $sync["Form"].Add_ContentRendered({
     }
 
     $sync["Form"].Focus()
+    $sync["Form"].Dispatcher.BeginInvoke([System.Windows.Threading.DispatcherPriority]::Background, [action]{ Initialize-WinUtilRunspacePool | Out-Null }) | Out-Null
 })
 
 # The SearchBarTimer is used to delay the search operation until the user has stopped typing for a short period

speed-todo.md

@@ -44,11 +44,11 @@ WinUtil currently does too much work before the first GUI paint. Work from the t
 
 ## P5 - Defer Runspace Pool Startup
 
-- [ ] Move GUI runspace pool creation after first render when no automation mode is active.
-- [ ] Keep synchronous runspace pool creation for `-Preset` and `-Config`.
-- [ ] Prewarm the pool shortly after `ContentRendered` so later actions do not feel delayed.
-- [ ] Ensure closing the form disposes the pool if it was created.
-- [ ] Verify buttons that queue work create or reuse the pool safely.
+- [x] Move GUI runspace pool creation after first render when no automation mode is active.
+- [x] Keep synchronous runspace pool creation for `-Preset` and `-Config`.
+- [x] Prewarm the pool shortly after `ContentRendered` so later actions do not feel delayed.
+- [x] Ensure closing the form disposes the pool if it was created.
+- [x] Verify buttons that queue work create or reuse the pool safely.
 
 ## P6 - Asset And Theme Cost