The real problem is deeper, maybe in the code...
With an i9 9900K, 32GB of DDR4 3200mhz, a RTX 4070 Ti, SSD NVME: The first fly is fine, 90 fps+...but THEN..the second one, the FPS got cut by half... then the thrid one fps got again cut by half...
Ending with 3 fps after like 5 6 fly running at the same time..and its reproductible, just get the first stock rocket in the game, throw it in the space, and go vab to reload one...after a few lunch, the game become unplayable ..even with small stock rocket...