Gaming on bootcamp with an egpu. Performance faltering? Best driver for a Radeon VII? Engine optimizations?  

I'm aware that performance is limited on an external gpu.  With a Core i7/32 GB Mac Mini + a Radeon VII (Windows Server LTSC 2k19), I was looking at anywhere between 5%-20% hit on any title at 40K/60fps for the last year.

Just earlier this year, I punched through Doom Eternal at Ultra 4K 70 fps, Resident Evil 3 at Ultra 60 fps and Metro Exodus at High 4K 60 fps.  In the past I slashed through Division 2 at High 4K 55 fps, Forza Horizon 4 Ultra 4K 60 fps and Devil May Cry Ultra 4K 80 fps.  However, as of late, I've been seeing a massive deterioration in performance.  (Without any gpu changes, no less).  Gears 5 barely hovers at 1440p 35-40 fps at high settings, which is more of a 40% hit.  State of Decay 2 is pinned at 4K, high settings at 40-45 fps.  And Warzone runs like garbage.  It seems like any title that uses Unreal Engine 4 takes a monstrous hit from egpus.

Worst still is that, running Windows Server 2019, to dodge the Error 12 bug, I updated my drivers to try to fix the performance and got...even worse performance.  Now I'll have to DDU and reinstall and hope I can recapture the old magic.

If the titles looked better, I'd say that it's logical that performance would dip.  But that doesn't seem to be the case.  Was wondering if anyone else is suffering with flagging performance also?