I would suggest monitoring RAM usage in the background during these excessively long load periods. It’s possible you are being affected by a memory leak issue that might have a hand in this. Maybe my posts here will help some…
More Performance Controls - #2 by powbam
AMD Ryzen 7 2700X OC’d 3.7-41GHz 8 Cores 16 Logical
XFX Radeon RX 580 4GB DDR5
16GB’s DDR4-3200 (2 x 8GB’s @1600 MHz ea.)
I just timed loading a save (1 min 42 sec) then timed exiting to menu (31 sec).