If it's damage calcs then that's CPU. Maybe the CPU is overheating and throttling.
I don't see any slowdown here mines an I7 6700k at 4.5 Ghz..


Regards,

Polovski
OBD Software, developers of epic, immersive, unique flight sims;
Wings Over Flanders Fields & Wings Over The Reich
https://www.overflandersfields.com
https://www.wingsoverthereich.com