I have seen slight drop in FPS when there is a lot of bullets in the air at the same time. I haven't looked into it much but I have a feeling that it is due to ballistic calculation bogging down the CPU.
This gave me an idea. Ballistics should maybe have it's own CPU-core if possible in the future, like sound has it's own in the current version. :smartass:
Edit: Sorry for off topic, and sorry if I am wrong...