Index: binaries/data/mods/public/simulation/ai/common-api/entitycollection.js
===================================================================
--- binaries/data/mods/public/simulation/ai/common-api/entitycollection.js
+++ binaries/data/mods/public/simulation/ai/common-api/entitycollection.js
@@ -84,9 +84,10 @@
 		filter = { "func": filter, "dynamicProperties": [] };
 
 	let ret = new Map();
-	for (let [id, ent] of this._entities)
+	this._entities.forEach((ent, id) => {
 		if (filter.func.call(thisp, ent, id, this))
 			ret.set(id, ent);
+	});
 
 	return new m.EntityCollection(this._ai, ret, this._filters.concat([filter]));
 };
Index: binaries/data/mods/public/simulation/ai/petra/garrisonManager.js
===================================================================
--- binaries/data/mods/public/simulation/ai/petra/garrisonManager.js
+++ binaries/data/mods/public/simulation/ai/petra/garrisonManager.js
@@ -64,6 +64,8 @@
 		}
 	}
 
+	const enemyEnts = gameState.getEnemyEntities().values();
+
 	for (let [id, data] of this.holders.entries())
 	{
 		let list = data.list;
@@ -130,7 +132,7 @@
 		{
 			let range = holder.attackRange("Ranged") ? holder.attackRange("Ranged").max : 80;
 			let around = { "defenseStructure": false, "meleeSiege": false, "rangeSiege": false, "unit": false };
-			for (let ent of gameState.getEnemyEntities().values())
+			for (let ent of enemyEnts)
 			{
 				if (ent.hasClass("Structure"))
 				{