Disable crowd neighbours building for optimisation

src/DotRecast.Detour.Crowd/DtCrowd.cs

@@ -425,11 +425,13 @@ namespace DotRecast.Detour.Crowd
             // Optimize path topology.
             UpdateTopologyOptimization(agents, dt);
 
+            #region Disabled for performance issues
             // Register agents to proximity grid.
-            BuildProximityGrid(agents);
+            // BuildProximityGrid(agents);
 
             // Get nearby navmesh segments and agents to collide with.
-            BuildNeighbours(agents);
+            // BuildNeighbours(agents);
+            #endregion
 
             // Find next corner to steer to.
             FindCorners(agents, debug);