Significant Ue4 performance downgrade after upgrading from Windows 1803 to 1809 (1903)

We’ve had packaged project which runs stable 90fps in VR (Oculus Rift), it was packaged in 4.19.
But, after we upgraded Windows it is now very unstable (drops to 45 most of the time).
I’ve tried all the Windows versions, installed all the latest drivers, configured all the power saving, gaming mode, nvidia performance mode etc. etc. but nothing helps.
We also updated the project to 4.22 and repackaged it - nothing changes.
I’ve got several exactly the same machines (Zotac VR GO), so we easily figured out that the problem start when we upgrade from 1803 to any of the newer versions.

We’ve also noticed that all the projects and UE4 itself run much worse on newer Windows than they did before.
Can anyone share hints about optimizing Windows/UE performance to solve the problem?
We are completely out of ideas.

Thanks for your help!