Some time back, I was working on a game in Unity 4.6 that relied very heavily on the use of the built in Unity NavMesh system. The game was completed and shipped, but now I'm looking into re-releasing the game and in doing so, I've updated to Unity 5. In Unity 5 though, the game now suffers from a tremendous drop in frame rate (as in 5 to 10 seconds per frame as opposed to 30-60 frames per second). Running the deep profiler points me towards a process called "Crowd.Proximity.Collect" under the NavMeshManager which appears to be pretty much entirely responsible for the drop in performance. While I normally find Unity to be well-documented, I haven't been able to find anything related to this process. Interestingly enough this only seems to happen when all of the NavMesh Agents in the scene are idle. If the player starts moving, this Crowd.Proximity.Collect process goes away and the frame rate returns to normal levels. Screenshots of the profiler are attached.