I have done most of these debugging steps. 3090 FE / 8700k dips to as low as 80 FPS in Europa. Average around 130. 1440p. Turning off vsync and uncapping frames I can get as high as 200. But the min is the same. The best help I have seen so far is following this guide: https://www.bungie.net/en/Help/Article/49656 But using 2 instead of 0. That made the FPS drops less noticeable, but the frames do drop.