Slow performance in no-rendering mode

hi all, I am running CARLA in no_rendering_mode and only adding the pedestrian NPCs to the world. I am testing two scenarios: 1-static, when pedestrians are static, and 2-ai, when they are controlled by ai.walker. I have noticed that FPS drops significantly when the AI walking is enabled and also with the number of NPC added to the world.
15 walkers:

  • (static) : 2000 FPS
  • (controlled) : 660 FPS

33 walkers:

  • (static) : 1100 FPS
  • (controlled) : 250 FPS

100 walkers:

  • (static) : 500 FPS
  • (controlled) : 82 FPS

if the NPCs are static what could be the reason for the slowdown, any ideas? Also, is there a way to avoid ai.walker overhead, e.g. by ignoring obstacle avoidance etc?
Thanks!