"Maybe it's about Light Shaft?"

This fps drop is from the patch after Light Shaft. I tested Light Shaft performance and was the same!I was like WoW no hit on performance! And stratis would have been hit by that, but its fine.Is just on altis, and they did some changes in altis, actually on tuesday "01-10-2013 Several bug fixes for Altis".

safe and careless mode.

"lower weapon, walk slowly --> your animation will stuck but you will continue moving" is probably the same bug!

"Can't hurt to have a module for it of course." there is one now!Have you checked? And caches objects too, like vehicles, chairs, fences...what ever you put on the map! It calls Simulation Manager! Check! And you can change the distance!

EOS by BangaBob is nice and you get a little better performance (10-15%)compare to cB AI Unit Caching Wolffy from my testing. But EOS does not let you choose what you want and cB lets you, plus is much easier to play with unit mods, EOS gets complicated. What we need is something like EOS that caches all the units (better performace) but lets you choose what you want!