Microsoft issued an advisory that signed PowerShell cmdlets may run slower if Windows is having network connectivity problems. When a signed PowerShell script is executed it will connect to the following Microsoft Certificate Trust List (CTL) URLs in order to verify the certificate. If the computer is experiencing network connectivity issues and is unable to access these URLs, the signed script may take longer than expected to execute. Microsoft states you can configure a group policy that stops Windows from automatically updating the trusted and untrusted CTLs from Microsoft.
Source: https://www.bleepingcomputer.com/news/microsoft/microsoft-explains-why-signed-powershell-cmdlets-may-run-slow/