https://www.youtube.com/watch?v=Hdb4iybN8gg

Game mode is supposed to be turned on or off for each game individually, so perhaps MS decided that there was no need for a global setting. Why Windows would think SONAR is a game and turn it on when running it is a mystery. In any case the link below purports to show how to disable game mode universally in the registry:
https://www.addictivetips.com/windows-tips/disable-game-mode-in-fall-creators-update-windows-10/
 

I've got updates set to the "slow ring" mode, so I haven't got the latest creator update. I still have the selector to turn it off but I'll be doing a registry hack as soon as the new version arrives.

This is an "ONLY" SONAR computer. No games, no office, no mails, I never had a xbox. Just audio production 24/7 for customer.
When I start the Command Center there is for nearly 2 minutes the message "you are not logged in". Only after almost 2 minutes I'm logged in. That is the same time SONAR needs to start.
My second DAW starts SONAR in 5 seconds and is logged into the Command Center in 1 second.
They are the same computers Intel i7-6700K 4GHz 32 GB, 250GB SSD.
 
Something prevents on my DAW 1 the fast authorization and login.
The internet is very fast, that is not the problem.
 
 

This is why large system IT people are staying with W7. 
Have you thought of reverting to W7? 
Otherwise the Enterprise version might be the safest bet. 

@Cactus Music
1995 - 2000 I was system IT expert.
I would never go back to W7. Our job is to digitize thousends of tapes and vinyl. W10 is so much faster then W7 by rendering with iZotope RX and Wave plugins.
I can everytime go back to an backup from the OS. Every week I make (automatically) a systembackup with historicised backups from all DAWs. This is beacuse we work on government and municipal contracts with confidentiality (I hope google has translated correct).
First I didn't know - But my colleague says the slow open time was 24 hours later as the Fall Creator Update was installed. Directly after the Update SONAR starts very fast. So anything happend subsequently in this 24 hours. Maybe Windows has installed some little patch one day later.
But the second problem is, that SONAR sends a permanent tone to my Waldorf Blofeld by starting SONAR.
  
So I will go back to the "OS Backup 2017-10-22" and have a look what happens.
 

Solved:
The slow start is up to Malwarebytes (internet protection software, for example Ransomeware). Since a few days Malwarebytes blocks anything, that SONAR needs to start - maybe to authenticate the Username.
But it is strange that my second DAW is also protected with Malwarebytes and SONAR starts in 5 seconds.