I just tried the Aerial Battle-Dover QMB mission which is an airstart. This time I had a solid FPS in the 90s+ (often well over 100) for the whole 5 or so minutes of the mission (lots of looking over my shoulder which seemed not to break anything this time)....
...then I got shot down (probably spent too much time looking at the FPS counter instead of the baddies).
So I hit exit, and then "restart" and bang ... FPS stuck in the low 30s again for the next run of the same mission
Something is definitely knocking out the benefits of the RadeonPro settings somewhere along the line. God this game is so good (despite all its flaws and missing/broken features) but it is so damn frustrating at times.
Oh well.