inplace upgrade Windows 2008 to Windows 2012r2 - no GUI

Finally I upgraded one of out-of-support servers - from Windows 2008 through Windows 2008r2 to Windows 2012r2. I had some issue with no boot device error (0x7b), but at the end upgrade of the server was finished. After logon - black screen, no GUI, I could run task manager, from task manager I could run explorer.exe (but only with the highest privileges) and Start Menu was strange.
I tried to make Windows Update, no effect - searching for updates (from WSUS) was never ending - few hours so I installed kb3138615, after restart and few minutes - voile la - there are - missing 202 patches, but every attempt to download and install patches failed - from GUI and command prompt.
Quick investigation - plenty of 10020 DistributedCOM Errors "The machine wide Default Launch and Activation security descriptor is invalid... The security permission can be corrected using the Component Services administrative tool."
I modified permissions and GUI came back after restart.

Windows 10 can't access Windows 2008 share - SMB1 is missing?

Yes, in Windows 10 from 1709 is missing, but... I had Windows 2008 Server with SMB2 disabled. So:
HKLM\System\CurrentControlSet\Services\LanmanServer\Parameters
Smb2, DWORD, 1 - enabled, 0 - disabled
Restart required.

DNS performance on Windows

Just to remember: I've got experience with heavy loaded domain controller with queries rate above 40k per second (yes, 40 thousand per second). The main problem on this virtual domain controller it was high cpu0 utilization and low load on other cpu. As I can remember - it was VMWare vm with 16 cores (virtual cores on operating system). What should be done in this case to improve performance? Upgrade of virtual hardware and network subsystem.