Optimization isnt really possible, as its not the games Assets, but the engine thats unoptimized, so till SBZ upgrades to UE5 and not UE4.27 it will be unoptimized

https://www.nexusmods.com/payday3/mods/36

really the only "optimisation" mod there is, but it doesn't to much so who knows if it does work well

engine.ini mod