I'll add my observations as well for 2020. Running a 4080 Super with 9800x 3D, downscaling ALL textures (VC, cabin etc) to 2K, hiding the EFB, and hiding the cabin, as well as lowering the gauge refresh rate nets me about 3-5 FPS in most scenarios. But, compared to the 146, F28, Fenix, PMDG products, and others; I'm running well lower 15-25+ FPS overall (typically 30-45 FPS for the Avro, 70-80+ for others in the same airport/weather/traffic scenarios). The RJ is definitely one of the hardest hitting products in my sim. I think I've exhausted most of the tricks trying to squeeze some more performance out of it, and would love to hear if any further optimizations could be made for it someday.
Open to any other ideas anyone may have!