Direct answer

Async pathfinding moves some route calculations away from the primary tick workload. It does not mean mob AI, navigation state changes or all entity updates become safe to execute from arbitrary threads.

How to check it

  1. Check the generated config/leaf-global.yml for an async.async-pathfinding section; the published reference documents async.async-pathfinding for Leaf 1.21.1.
  2. Profile a mob-heavy scene where pathfinding actually contributes to tick time. Record mob behavior, plugin versions and CPU utilization.
  3. Review server logs for worker exceptions and test plugins that modify entity navigation or movement.

What to change

On a matching build, compare the built-in enabled setting with the same test workload after a restart:

async:
  async-pathfinding:
    enabled: true

Leave worker sizing on the generated automatic setting initially; giving workers too many threads can crowd out chunk, region or JVM work.

Compatibility and safety

The public Leaf configuration reference is tied to its 1.21.1 branch. Do not copy this key to a newer build unless the generated file or matching version docs confirms that the option still exists.

Software and version notes

The cited Leaf global config page explicitly describes the 1.21.1 branch; newer Leaf builds may have different keys, defaults or feature support. Verify config/leaf-global.yml generated by your actual server.

Verify the result

Re-test both pathfinding CPU cost and whether mobs navigate doors, obstacles and farms normally. Restore the previous value if AI behavior regresses.

References