powershell.exe call from batch file unbearable slow after upgrading to windows 10

I'm having some trouble with a `.bat`->`.ps1` call in my build process after moving from Win7 to Win10 (1607 LTSB) - the call to PowerShell, that took less than 100msec on Win7 now takes 10sec+ on Win10 on certain hosts :-(

The call looks like this: `powershell -ExecutionPolicy Bypass -NonInteractive %scriptfile%`

Startup-performance of ISE and PowerShell.exe from start-menu is good.

I wasn't able to dig up anything helpful so far...

* PoSh 5.1 on both, Win7 and Win10, PSProfile is clean apart from a couple of aliases
* $env:PATH is "clean" apart from a couple of folders that have been added on purpose - removing those didn't improve the situation.
* already did "ngen update" - problem still occurs.

I've create a little helper script that measures startup-performance of PowerShell from different starting points: no luck with this either, on Win7 and most of my Win10 machines startup-time is way below 1sec.

anybody here who has already solved this riddle?

Solved! - it's been UAC all along :-(

Solution: disable UAC for the user that's running the scriots or make sure the first script that calls the others is being run as administrator / elevated.

Not sure why UAC is causing these delays, and I'm certain there are cases where this is not an option - but for me this is solved by ensuring the first script is elevated + disabling UAC for dev boxes.

I had a similar problem - scripts taking multiple seconds to start.

The problem turned out to be a combination of two factors:

* I had `ExecutionPolicy` force-set to `RemoteSigned` via GPO (run `Get-ExecutionPolicy -List` and check the value for `MachinePolicy`)
* I had quite a few processes running, so that enumerating them was taking a long time

...so it was fixed by a restart. (I think [overriding the GPO-set value](

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) would also work, but I didn't try it.)

---
What didn't work:

* Disabling the loading of my profile (`powershell -NoProfile`)
* [Running ngen to generate native images for an assembly and its dependencies and install them in the Native Images Cache](

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)
* [Disable module autoloading (introduced in v3) with `$PSModuleAutoloadingPreference = 'none'`](

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), i.e. `powershell.exe -NoProfile -ExecutionPolicy Bypass -command "$PSModuleAutoloadingPreference = 'none'; & path\to\script.ps1"`
* ["Use legacy console" in the shortcut properties](

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)
* [Disabling UAC](

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)

I noticed that simply running PowerShell was relatively fast, only script execution (via command-line parameters or the [`&` / Call operator](

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)) was slow. For instance I could run the script by piping it to powershell's stdin, which didn't incur the slowdown:

type "script.ps1" | powershell.exe -noprofile -nologo -executionpolicy Bypass -file -

At this point I tried [troubleshooting with ProcMon](

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), which didn't show any long calls.

Next I tried opening Process Explorer to check the stack of the powershell.exe process while it was loading the script. The top of the stack was:

ntdll.dll!RtlGetNativeSystemInformation+0x14
KERNEL32.DLL!lstrcmpA+0x12d
KERNEL32.DLL!CreateToolhelp32Snapshot+0x108
[Native Frame: IL Method without Metadata]
[Managed to Unmanaged Transition]
System.Management.Automation.dll!System.Management.Automation.PsUtils.GetParentProcess+0x73
System.Management.Automation.dll!System.Management.Automation.Internal.SecuritySupport.GetExecutionPolicy+0x138

which led me to [issue #2578](

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) that explained the behavior I was seeing.