This is just a simple registry hack for Windows 10 pointing it to a dead Windows Update Server, it will also block sharing updates with Windows clients within the same LAN, a feature in Win 10 to save resources when too many of them are nearby.
It shouldn't be on a shared drive since the code is proprietary

rather explain what users can do in a simple post could earn you some gratitude before coins.
However, starting from Windows 8 if you don't update your system for a while ( you can't really skip the forced updates with restarts) your system will slow down, test it by not updating for 90+ days or so.
I use Pihole to block all incoming traffic from servers I do not wish to use

and update only when I cannot avoid it anymore but that doesn't stop random apps being installed even though I had disabled everything possible.
For business, WSUS and Active Directory does the job.