I have exactly the same frame drops.
I am starting cold & dark at 60s-70s fps parked everything is smooth and nice. When i am adding waypoints & airways of the flight route fps goes to to 30-35.
I understand how demanding CRJ systems are but is it normal to loose almost 30fps ?
Flybywire A32NX had exactly the same issue when importing a flight plan but they fixed on latest updates
PC spec: 8700 @5.1ghz delidded / 3090 Asus Rog Strix OC / Asus Rog PG279Q G-sync monitor / 32 gskill ram 3200