Windows Server 2016 updates slow?

Try disabling Real-Time Windows Defender Scanning during install:

[PowerShell] Set-MpPreference -DisableRealtimeMonitoring $true [/PowerShell]

If this makes your updates quicker, you can permanently add an exception for the Windows Update folders:

• C:\Windows\CbsTemp
• C:\Windows\Logs\CBS
• C:\Windows\SofwareDistribution

Remember to enable Real-Time Scanning after done!

[PowerShell] Set-MpPreference -DisableRealtimeMonitoring $false [/PowerShell]