diff --git a/ClassCreep.js b/ClassCreep.js
index 785bda4..d55fa60 100644
--- a/ClassCreep.js
+++ b/ClassCreep.js
@@ -18,31 +18,38 @@ class _Creep extends Creep {
 		this.memory.path = undefined;
 	}
 
-	findTarget(target) {
+	findTarget(TARGET) {
 		if (this.memory.target == undefined) {
-			this.memory.target = this.pos.findClosestByPath(target);
-			if (this.memory.target == null) {
-				this.memory.target = undefined;
-				return ERR_NOT_FOUND;
-			}
+			const target = this.pos.findClosestByPath(TARGET);
+			if (target == null) return ERR_NOT_FOUND;
+			else this.memory.target = target.id;
 		}
 		return OK;
 	}
 
-	findTarget(target, filter) {
+	findTarget(TARGET, filter) {
 		if (this.memory.target == undefined) {
-			this.memory.target = this.pos.findClosestByPath(target, filter);
-			if (this.memory.target == null) {
-				this.memory.target = undefined;
-				return ERR_NOT_FOUND;
-			}
+			const target = this.pos.findClosestByPath(TARGET, filter);
+			if (target == null) return ERR_NOT_FOUND;
+			else this.memory.target = target.id;
 		}
 		return OK;
 	}
 
 	harvestSource() {
-		if (this.findTarget(FIND_SOURCES) == ERR_NOT_FOUND) return;
-		const target = Game.getObjectById(this.memory.target.id);
+		if (this.findTarget(FIND_SOURCES, {
+			filter: (s) => {
+				const area = s.room.lookAtArea(s.pos.y - 1, s.pos.x - 1, s.pos.y + 1, s.pos.y + 1, true);
+				var free_space = 0;
+				area.forEach(entry => {
+					if (entry.type == "creep") free_space--;
+					else if (entry.type == "terrain" && entry.terrain == "plain") free_space++;
+					else if (entry.type == "terrain" && entry.terrain == "swamp") free_space++;
+				});
+				return free_space > 0;
+			}
+		}) == ERR_NOT_FOUND) return;
+		const target = Game.getObjectById(this.memory.target);
 		if (this.moveToTarget() == OK) {
 			this.harvest(target);
 			this.toggleChargeMode();
@@ -70,13 +77,14 @@ class _Creep extends Creep {
 	supplyStructures() {
 		if (this.findTarget(FIND_MY_STRUCTURES, {
 			filter: (s) => {
-				return s.structureType == STRUCTURE_SPAWN ||
+				return (s.structureType == STRUCTURE_SPAWN ||
 					s.structureType == STRUCTURE_EXTENSION ||
 					s.structureType == STRUCTURE_TOWER ||
-					s.structureType == STRUCTURE_STORAGE;
+					s.structureType == STRUCTURE_STORAGE)
+					&& 0 < s.store.getFreeCapacity();
 			}
 		}) == ERR_NOT_FOUND) return;
-		const target = Game.getObjectById(this.memory.target.id);
+		const target = Game.getObjectById(this.memory.target);
 		if (this.moveToTarget() == OK) {
 			this.transfer(target, RESOURCE_ENERGY);
 			this.toggleChargeMode();
@@ -84,14 +92,9 @@ class _Creep extends Creep {
 	}
 
 	upgradeRoom() {
-		if (this.findTarget(FIND_MY_STRUCTURES, {
-			filter: (s) => {
-				return s.structureType == STRUCTURE_CONTROLLER;
-			}
-		}) == ERR_NOT_FOUND) return;
-		const target = Game.getObjectById(this.memory.target.id);
+		this.memory.target = this.room.controller.id;
 		if (this.moveToTarget() == OK) {
-			this.upgradeController();
+			if (this.upgradeController(this.room.controller) == OK) return;
 			this.toggleChargeMode();
 		}
 	}
@@ -126,30 +129,27 @@ class _Creep extends Creep {
 		}
 	}
 
-	// Moves to the target.
 	moveToTarget() {
-		if (this.pos.inRangeTo(this.memory.target.pos.x, this.memory.target.pos.y, 1)) {
+		const target = Game.getObjectById(this.memory.target)
+		if (this.pos.inRangeTo(target.pos.x, target.pos.y, 1)) {
 			this.memory.path = undefined;
 			return OK;
 		}
+		if (this.pos.inRangeTo(target.pos.x, target.pos.y, 5)) {
+			this.moveTo(target)
+			return ERR_BUSY;
+		}
 		if (this.memory.path == undefined) {
-			var path = this.pos.findPathTo(this.memory.target.pos, {
+			this.memory.path = this.pos.findPathTo(target.pos, {
 				ignoreCreeps: true, range: 1
 			});
-			path.reverse();
-			this.memory.path = path;
 		}
-		const step = this.memory.path.pop();
-		var response = this.move(step.direction);
-		if (response == OK) {
-			if (this.pos.x == step.x &&
-				this.pos.y == step.y) return ERR_BUSY;
-			response = this.moveTo(this.memory.target.pos.x, this.memory.target.pos.y);
-		}
-		if (response == OK || response == ERR_INVALID_ARGS || response == ERR_NOT_FOUND) {
+		const response = this.moveByPath(this.memory.path);
+		if (response == OK) return ERR_BUSY;
+		if (response == ERR_INVALID_ARGS || response == ERR_NOT_FOUND) {
+			this.moveTo(target);
 			this.memory.path = undefined;
 			return ERR_BUSY;
 		}
-		this.memory.path.push(step);
 	}
 }
diff --git a/ClassRoom.js b/ClassRoom.js
index 67fe4dd..15b2020 100644
--- a/ClassRoom.js
+++ b/ClassRoom.js
@@ -15,16 +15,8 @@ class _Room extends Room {
 
 	//#region Checks
 
-	// Is the level changed?
-	isNewLevel() {
-		if (this.memory.level == undefined) this.memory.level = -1;
-		const value = this.controller.my && this.controller.level != this.memory.level;
-		if (value) this.memory.level = this.controller.level;
-		return value;
-	}
-
 	// Is the max amount of construction sites achieved?
-	isConstructionQueueFull() { return this.find(FIND_CONSTRUCTION_SITES).length > 90; }
+	canConstruct() { return this.find(FIND_CONSTRUCTION_SITES).length < 90; }
 	//#endregion
 
 	//#region Construcion
@@ -62,7 +54,6 @@ class _Room extends Room {
 		});
 
 		// Build a road for every permutation of the targets.
-		// TODO: When performance to high make this loop recoverable.
 		for (let i = 0; i < target_array.length; i++) {
 			const begin = target_array[i];
 			for (let j = 0; j < target_array.length; j++) {
diff --git a/ClassSpawn.js b/ClassSpawn.js
index d43fb53..b116582 100644
--- a/ClassSpawn.js
+++ b/ClassSpawn.js
@@ -14,7 +14,7 @@ class _Spawn extends StructureSpawn {
 
 		switch (role) {
 			case ROLE_HARVESTER:
-				return roleCount < 5;
+				return roleCount < 10;
 				break;
 
 			default:
diff --git a/_creeps.js b/_creeps.js
index 5b1afbf..ad19946 100644
--- a/_creeps.js
+++ b/_creeps.js
@@ -1,3 +1,5 @@
+const { round } = require("lodash");
+
 module.exports = {
 	// Gets called when recompiling and when Restart command is called.
 	start: function () {
@@ -11,7 +13,10 @@ module.exports = {
 	update: function () {
 		for (const creep_name in Memory.creeps) {
 			const creep = Game.creeps[creep_name];
-			if (creep == undefined) delete Memory.creeps[creep_name];
+			if (creep == undefined) {
+				delete Memory.creeps[creep_name];
+				return;
+			}
 			switch (creep.memory.role) {
 				case ROLE_HARVESTER:
 					if (creep.memory.recharge) creep.harvestSource();
diff --git a/_rooms.js b/_rooms.js
index be0de35..3b55701 100644
--- a/_rooms.js
+++ b/_rooms.js
@@ -9,9 +9,9 @@ module.exports = {
 	update: function () {
 		for (const room_name in Game.rooms) {
 			const room = Game.rooms[room_name];
-			if (room.isNewLevel()) {
+			if (Game.time % 1000 == 0) {
 				// Place new building types if the max construcion sites isn't achieved yet.
-				if (!room.isConstructionQueueFull()) {
+				if (room.canConstruct()) {
 					room.planRoads();
 					room.planStructures();
 				}