NPCs and Open world

If guess I have to use a collision sphere on the player then execute some functions on the overlapped NPC actors but what are the things that I can do to save most performance?

  • Make the NPC skeletal mesh invisible
  • Stop Logic on brain component (using behavior tree)
  • Remove collision on caspule
  • Set actor tick enabled to disabled
  • ???

I did some stress test on an empty level on a plane with a dynamic skylight and ~100 AI but even with this 4 steps, FPS are still far bellow the FPS without AI at all