Since SU12 I have been having much poorer performance than previously. Before the update I have had, almost continuously from day one, smooth performance and since upgrading my broadband it has been very good. With a mix of settings, but mostly high, I have been comfortably achieving 45fps and 15-29ms but I could run at 60fps without issue . Since the update my frame rate dropped to mid 20s and I was experiencing stutters and random freezes (around 5 secs). Yesterday, I had the same symptoms as the OP. I don’t usually run with the metrics visible but after having been forced to abandon the flight as I was simply unable to land I tried again with the metrics displayed on a second monitor, on the ground I was seeing 14fps and 90ms, GPU at 99% and VRAM maxed out (7.9Gb). GPU temps were fine and the fans were running at fairly low revs. I am off to try some diagnostics now but I had just downloaded the latest AMD Radeon drivers and I rolled that back last night before retiring hurt. I will come back if I find anything.
Rig:
MSI AMD X570 Unify: RX5700XT 8Gb VRAM: Ryzen 7 5800X: 32Gb RAM @ 3600: 1TB SSD: 2K 34" and 1080 27" Monitors.