I have two questions about Navmeshes and Obstacles: 1. Is there a limit on how many obstacles you can have at once? That is, does it start affecting performance if you have too many of them? 2. As I understand it, an obstacle that is not moving can be set to carve a hole in a navmesh. Is that constantly updated (and therefore would need to keep an obstacle in place), or is there a way to 'freeze' the navmesh so that it doesn't update? What I mean by that is, can you drop an obstacle in place, have it carve a hole, freeze the navmesh in some way, and then remove the obstacle without the hole disappearing?