Index: binaries/data/mods/public/simulation/components/ProductionQueue.js
===================================================================
--- binaries/data/mods/public/simulation/components/ProductionQueue.js
+++ binaries/data/mods/public/simulation/components/ProductionQueue.js
@@ -1,4 +1,3 @@
-var g_ProgressInterval = 1000;
 const MAX_QUEUE_SIZE = 16;
 
 function ProductionQueue() {}
@@ -34,6 +33,11 @@
 		Resources.BuildSchema("nonNegativeDecimal", ["time"]) +
 	"</element>";
 
+/**
+ * Interval of timer where the queue is updated.
+ */
+ProductionQueue.prototype.PROGRESS_INTERVAL = 1000;
+
 ProductionQueue.prototype.Init = function()
 {
 	this.nextID = 1;
@@ -63,7 +67,7 @@
 	//     "timeRemaining": 10000, // msecs
 	//   }
 
-	this.timer = undefined; // g_ProgressInterval msec timer, active while the queue is non-empty
+	this.timer = undefined; // PROGRESS_INTERVAL msec timer, active while the queue is non-empty
 	this.paused = false;
 
 	this.entityCache = [];
@@ -356,8 +360,6 @@
 			// thing twice.
 			var cmpTechnologyManager = QueryOwnerInterface(this.entity, IID_TechnologyManager);
 			cmpTechnologyManager.QueuedResearch(templateName, this.entity);
-			if (this.queue.length == 0)
-				cmpTechnologyManager.StartedResearch(templateName, false);
 
 			this.queue.push({
 				"id": this.nextID++,
@@ -382,12 +384,8 @@
 
 		Engine.PostMessage(this.entity, MT_ProductionQueueChanged, { });
 
-		// If this is the first item in the queue, start the timer
 		if (!this.timer)
-		{
-			var cmpTimer = Engine.QueryInterface(SYSTEM_ENTITY, IID_Timer);
-			this.timer = cmpTimer.SetTimeout(this.entity, IID_ProductionQueue, "ProgressTimeout", g_ProgressInterval, {});
-		}
+			this.ProgressTimeout();
 	}
 	else
 	{
@@ -538,16 +536,12 @@
 	this.CalculateEntitiesList();
 };
 
+/**
+ * Reset the queue to refund any resources when destroyed.
+ */
 ProductionQueue.prototype.OnDestroy = function()
 {
-	// Reset the queue to refund any resources
 	this.ResetQueue();
-
-	if (this.timer)
-	{
-		var cmpTimer = Engine.QueryInterface(SYSTEM_ENTITY, IID_Timer);
-		cmpTimer.CancelTimer(this.timer);
-	}
 };
 
 /*
@@ -679,18 +673,20 @@
 	// Check if the production is paused (eg the entity is garrisoned)
 	if (this.paused)
 		return;
-	// Allocate the 1000msecs to as many queue items as it takes
+
+ 	// Allocate the 1000msecs to as many queue items as it takes
 	// until we've used up all the time (so that we work accurately
 	// with items that take fractions of a second)
-	var time = g_ProgressInterval;
+	let time = this.PROGRESS_INTERVAL;
+
 	var cmpPlayer = QueryOwnerInterface(this.entity);
 
-	while (time > 0 && this.queue.length)
+	while (this.queue.length)
 	{
 		var item = this.queue[0];
 		if (!item.productionStarted)
 		{
-			// If the item is a unit then do population checks
+			// If the item is an unit then do population checks.
 			if (item.unitTemplate)
 			{
 				// If something change population cost
@@ -712,9 +708,10 @@
 
 				// Unset flag that training is blocked
 				cmpPlayer.UnBlockTraining();
+
+				Engine.PostMessage(this.entity, MT_TrainingStarted, { "entity": this.entity });
 			}
-
-			if (item.technologyTemplate)
+			else if (item.technologyTemplate)
 			{
 				// Mark the research as started.
 				var cmpTechnologyManager = QueryOwnerInterface(this.entity, IID_TechnologyManager);
@@ -722,17 +719,18 @@
 			}
 
 			item.productionStarted = true;
-			if (item.unitTemplate)
-				Engine.PostMessage(this.entity, MT_TrainingStarted, { "entity": this.entity });
+
+			if (!this.timer)
+				break;
 		}
 
 		// If we won't finish the batch now, just update its timer
 		if (item.timeRemaining > time)
 		{
 			item.timeRemaining -= time;
-			// send a message for the AIs.
+			// Send a message for the AIs.
 			Engine.PostMessage(this.entity, MT_ProductionQueueChanged, { });
-			break;
+			return;
 		}
 
 		if (item.unitTemplate)
@@ -740,14 +738,11 @@
 			var numSpawned = this.SpawnUnits(item.unitTemplate, item.count, item.metadata);
 			if (numSpawned == item.count)
 			{
-				// All entities spawned, this batch finished
+				// All entities spawned, this batch finished.
 				cmpPlayer.UnReservePopulationSlots(item.population * numSpawned);
-				time -= item.timeRemaining;
-				this.queue.shift();
-				// Unset flag that training is blocked
+				// Unset flag that training is blocked.
 				cmpPlayer.UnBlockTraining();
 				this.spawnNotified = false;
-				Engine.PostMessage(this.entity, MT_ProductionQueueChanged, { });
 			}
 			else
 			{
@@ -771,7 +766,7 @@
 					cmpGUIInterface.PushNotification(notification);
 					this.spawnNotified = true;
 				}
-				break;
+				return;
 			}
 		}
 		else if (item.technologyTemplate)
@@ -788,43 +783,60 @@
 				if (cmpSoundManager)
 					cmpSoundManager.PlaySoundGroup(template.soundComplete, this.entity);
 			}
+		}
 
-			time -= item.timeRemaining;
-
-			this.queue.shift();
-			Engine.PostMessage(this.entity, MT_ProductionQueueChanged, { });
-		}
+		// Directly process to the next item.
+		time -= item.timeRemaining;
+		this.queue.shift();
+		Engine.PostMessage(this.entity, MT_ProductionQueueChanged, { });
 	}
 
-	// If the queue's empty, delete the timer, else repeat it
+	// Start the timer when its the first item added to production.
+	if (!this.timer)
+		this.StartTimer();
+
+	// If the queue's empty, delete the timer.
 	if (this.queue.length == 0)
 	{
-		this.timer = undefined;
+		this.StopTimer();
 
 		// Unset flag that training is blocked
 		// (This might happen when the player unqueues all batches)
 		cmpPlayer.UnBlockTraining();
 	}
-	else
-	{
-		var cmpTimer = Engine.QueryInterface(SYSTEM_ENTITY, IID_Timer);
-		this.timer = cmpTimer.SetTimeout(this.entity, IID_ProductionQueue, "ProgressTimeout", g_ProgressInterval, data);
-	}
 };
 
 ProductionQueue.prototype.PauseProduction = function()
 {
-	this.timer = undefined;
 	this.paused = true;
+	this.StopTimer();
 };
 
 ProductionQueue.prototype.UnpauseProduction = function()
 {
 	this.paused = false;
-	var cmpTimer = Engine.QueryInterface(SYSTEM_ENTITY, IID_Timer);
-	this.timer = cmpTimer.SetTimeout(this.entity, IID_ProductionQueue, "ProgressTimeout", g_ProgressInterval, {});
+	this.StartTimer(true);
 };
 
+ProductionQueue.prototype.StartTimer = function()
+{
+	if (this.timer || this.paused)
+		return;
+
+	let cmpTimer = Engine.QueryInterface(SYSTEM_ENTITY, IID_Timer);
+	this.timer = cmpTimer.SetInterval(this.entity, IID_ProductionQueue, "ProgressTimeout", this.PROGRESS_INTERVAL, this.PROGRESS_INTERVAL, {});
+};
+
+ProductionQueue.prototype.StopTimer = function()
+{
+	if (!this.timer)
+		return;
+
+	let cmpTimer = Engine.QueryInterface(SYSTEM_ENTITY, IID_Timer);
+	cmpTimer.CancelTimer(this.timer);
+	this.timer = undefined;
+};
+
 ProductionQueue.prototype.OnValueModification = function(msg)
 {
 	// if the promotion requirements of units is changed,