Hello,
I had the same problem as you, and it's all gone since the new Nvidia Driver (390.65).
Well I think so, I just played 1 hour with the Mi8 and the Mig15, before this new driver DCS was freezing every 20 seconds, now I can fly freely, and re-learn to fly (I qui 10 years ago ;) )
Hope It will be the same for you!