Just to check what temps do you get on CPU and GPU ? 40FPS in the ship can also be temp related, then it restores when temp lowers, but doubtful if you get 15fps as soon as you enter a warzone though.
Warzones will be the heaviest areas for FPS , does turning nameplates off have an effect at all, this is something I have seen popup occasionally.
Turning off nameplates did nothing.
My CPUs are all running at 40-43 celsius in heavy warzone traffic. ANd my GPU is anywhere from 50-60 celsius in warzone traffic.