Windows 10 SAC has become a crapshoot for VDI. We use 1803 and get roughly 1m30s to 2m using UEM and AppVolumes Writables (which I want to get rid of). I’ve optimized this image using vFeller’s blog, Citrix tools, OSOT, and following VMware’s standard for building an image, but it just seems to be the way Windows operates and it looks like it’s primarily the “System” AppX packages causing it.
If you enable your AppReadiness logs you will probably see most of the time being consumed there. This is part of the shell load time that you would see in the logon monitor logs. It’s atrocious. And you can’t disable this service because then there’s a good chance the start menu won’t load.
I’m in the process now of building an LTSC image for the interim while we investigate building a custom wim that rips some of the crap out. It’s tough to do since MSFT built in protections against this by building dependencies between the system AppX packages and core system components like .NET.