After 10 mins, disk usage spikes and makes game unplayable.

There are a few things which you can check as any of them can create the problem you describe.

1. Make sure you have enough free space in C: On that note, clearing %temp% will be welcome.
2. Don't disable pagefile unless you have >= 32Gb RAM. 
3. Disable indexing service for all partitions.
4. Disable system protection (clear the restore points first)

    

5. Activate Game Mode

   

    

6. Make sure you have enough space on the partition where the game is store. The SSD is acting weird  once it gets loaded over 80% (just a day by day observation)

7. Control the background services. There are a lot of windows background processes running for programs which you are no use or are not open (Edge, Chrome, Opera, Phone link, Gamebar, MSStore). As example, this is how my computer starts

   

    

8. Set fixed value for shaders cache in nvidia control panel (switch from automatic to >5Gb).

9. From time to time clean the the partition C: using Disk Clean-Up

   

    

    I hope that helps.