So, close, but no cigar.
Popout windows (externalization) tanks fps from 50+ in DX12 down to 10-ish fps. In DX11 its as bad as it was before, but no worse, so there’s that.
Basically the half-fix for externalization has utterly crippled anyone that uses this feature now with touch cockpits.
And the bug that where when an externalized has a mouse over it all hardware controls of the plane are locked out are still there. 
I regret having changed my mind and installed this. I’m now dead in the water. But then again, so will ever other person using touch avionics on external touch screens going forward. And this isn’t in the patch notes, so pretty much pointless to report the issue.