I hope Edge fixes it but I wouldn't get my hopes up. Making crap up that AMD has removed DX9 optimisations is pure bullshit on the side of the developers. I have many DX9 games that would never class as AAA and they all run perfectly fine in DX9.
Rise of Flight
Steel Armor: Blaze of War
Divinity II Eco Draconis
As you can see every single one of these games are AAA DX9 titles. Obviously they all run like crap on my R9 290X. No matter what graphical setting or resolution I use I always get FPS in low 20s.
You will obviously note the sarcasm in my post. I spent a LOT of money on this sim only to see the developers point blank lie that AMD are at fault for my poor R9 290X performance. They even have the gall to claim ALL DX9 optimisations have been removed since Catalyst 12.XX. Strange that every other game I listed above (and man more) all run absolutely perfectly.
I suppose AMD singled out DCS series of sims for DX9 anti-optimisations. Yeah that's it.