diff --git a/core/src/com/unciv/logic/automation/Automation.kt b/core/src/com/unciv/logic/automation/Automation.kt
index b9a914e36d..8bc6d4f0b5 100644
--- a/core/src/com/unciv/logic/automation/Automation.kt
+++ b/core/src/com/unciv/logic/automation/Automation.kt
@@ -101,7 +101,7 @@ class Automation {
             chosenUnit = militaryUnits.filter { it.unitType== UnitType.Ranged }.maxBy { it.cost }!!
 
         else{ // randomize type of unit and take the most expensive of its kind
-            val chosenUnitType = militaryUnits.map { it.unitType }.distinct().filterNot{it==UnitType.Scout}.random()
+            val chosenUnitType = militaryUnits.map { it.unitType }.distinct().filterNot{it==UnitType.Scout}.toList().random()
             chosenUnit = militaryUnits.filter { it.unitType==chosenUnitType }.maxBy { it.cost }!!
         }
         return chosenUnit.name
diff --git a/core/src/com/unciv/logic/automation/ConstructionAutomation.kt b/core/src/com/unciv/logic/automation/ConstructionAutomation.kt
index b6db33b0a1..ce3b334782 100644
--- a/core/src/com/unciv/logic/automation/ConstructionAutomation.kt
+++ b/core/src/com/unciv/logic/automation/ConstructionAutomation.kt
@@ -18,8 +18,10 @@ class ConstructionAutomation(val cityConstructions: CityConstructions){
     val cityInfo = cityConstructions.cityInfo
     val civInfo = cityInfo.civInfo
 
-    val buildableNotWonders = cityConstructions.getBuildableBuildings().filterNot { it.isWonder || it.isNationalWonder }
-    val buildableWonders = cityConstructions.getBuildableBuildings().filter { it.isWonder || it.isNationalWonder }
+    val buildableNotWonders = cityConstructions.getBuildableBuildings()
+            .filterNot { it.isWonder || it.isNationalWonder }
+    val buildableWonders = cityConstructions.getBuildableBuildings()
+            .filter { it.isWonder || it.isNationalWonder }
 
     val civUnits = civInfo.getCivUnits()
     val militaryUnits = civUnits.filter { !it.type.isCivilian()}.size
@@ -118,6 +120,7 @@ class ConstructionAutomation(val cityConstructions: CityConstructions){
     private fun addWorkerChoice() {
         if(civInfo.getIdleUnits().any { it.name==Constants.worker && it.action== Constants.unitActionAutomation})
             return // If we have automated workers who have no work to do then it's silly to construct new workers.
+
         val citiesCountedTowardsWorkers = min(5, cities) // above 5 cities, extra cities won't make us want more workers
         if (workers < citiesCountedTowardsWorkers * 0.6f && civUnits.none { it.name==Constants.worker && it.isIdle() }) {
             var modifier = citiesCountedTowardsWorkers / (workers + 0.1f)
@@ -127,7 +130,8 @@ class ConstructionAutomation(val cityConstructions: CityConstructions){
     }
 
     private fun addCultureBuildingChoice() {
-        val cultureBuilding = buildableNotWonders.filter { it.isStatRelated(Stat.Culture) }.minBy { it.cost }
+        val cultureBuilding = buildableNotWonders
+                .filter { it.isStatRelated(Stat.Culture) }.minBy { it.cost }
         if (cultureBuilding != null) {
             var modifier = 0.5f
             if(cityInfo.cityStats.currentCityStats.culture==0f) // It won't grow if we don't help it
@@ -149,7 +153,7 @@ class ConstructionAutomation(val cityConstructions: CityConstructions){
     }
 
     private fun addWondersChoice() {
-        if (buildableWonders.isNotEmpty()) {
+        if (buildableWonders.any()) {
             fun getWonderPriority(wonder: Building): Float {
                 if (preferredVictoryType == VictoryType.Cultural
                         && wonder.name in listOf("Sistine Chapel", "Eiffel Tower", "Cristo Redentor", "Neuschwanstein", "Sydney Opera House"))
@@ -167,21 +171,20 @@ class ConstructionAutomation(val cityConstructions: CityConstructions){
                 return 1f
             }
 
-            val wondersByPriority = buildableWonders
-                    .sortedByDescending { getWonderPriority(it) }
-            val wonder = wondersByPriority.first()
+            val highestPriorityWonder = buildableWonders
+                    .maxBy { getWonderPriority(it) }!!
             val citiesBuildingWonders = civInfo.cities
                     .count { it.cityConstructions.isBuildingWonder() }
 
-            var modifier = 2f * getWonderPriority(wonder) / (citiesBuildingWonders + 1)
+            var modifier = 2f * getWonderPriority(highestPriorityWonder) / (citiesBuildingWonders + 1)
             if (!cityIsOverAverageProduction) modifier /= 5  // higher production cities will deal with this
-            addChoice(relativeCostEffectiveness, wonder.name, modifier)
+            addChoice(relativeCostEffectiveness, highestPriorityWonder.name, modifier)
         }
     }
 
     private fun addUnitTrainingBuildingChoice() {
-        val unitTrainingBuilding = buildableNotWonders.filter { it.xpForNewUnits > 0 }
-                .minBy { it.cost }
+        val unitTrainingBuilding = buildableNotWonders.asSequence()
+                .filter { it.xpForNewUnits > 0 }.minBy { it.cost }
         if (unitTrainingBuilding != null && (preferredVictoryType != VictoryType.Cultural || isAtWar)) {
             var modifier = if (cityIsOverAverageProduction) 0.5f else 0.1f // You shouldn't be cranking out units anytime soon
             if (isAtWar) modifier *= 2
@@ -192,8 +195,8 @@ class ConstructionAutomation(val cityConstructions: CityConstructions){
     }
 
     private fun addDefenceBuildingChoice() {
-        val defensiveBuilding = buildableNotWonders.filter { it.cityStrength > 0 }
-                .minBy { it.cost }
+        val defensiveBuilding = buildableNotWonders.asSequence()
+                .filter { it.cityStrength > 0 }.minBy { it.cost }
         if (defensiveBuilding != null && (isAtWar || preferredVictoryType != VictoryType.Cultural)) {
             var modifier = 0.2f
             if (isAtWar) modifier = 0.5f
@@ -208,7 +211,7 @@ class ConstructionAutomation(val cityConstructions: CityConstructions){
     }
 
     private fun addHappinessBuildingChoice() {
-        val happinessBuilding = buildableNotWonders
+        val happinessBuilding = buildableNotWonders.asSequence()
                 .filter { it.isStatRelated(Stat.Happiness)
                         || it.uniques.contains("Remove extra unhappiness from annexed cities") }
                 .minBy { it.cost }
@@ -222,7 +225,8 @@ class ConstructionAutomation(val cityConstructions: CityConstructions){
     }
 
     private fun addScienceBuildingChoice() {
-        val scienceBuilding = buildableNotWonders.filter { it.isStatRelated(Stat.Science) || it.name=="Library" } // only stat related in unique
+        val scienceBuilding = buildableNotWonders.asSequence()
+                .filter { it.isStatRelated(Stat.Science) || it.name=="Library" } // only stat related in unique
                 .minBy { it.cost }
         if (scienceBuilding != null) {
             var modifier = 1.1f
@@ -233,7 +237,7 @@ class ConstructionAutomation(val cityConstructions: CityConstructions){
     }
 
     private fun addGoldBuildingChoice() {
-        val goldBuilding = buildableNotWonders.filter { it.isStatRelated(Stat.Gold) }
+        val goldBuilding = buildableNotWonders.asSequence().filter { it.isStatRelated(Stat.Gold) }
                 .minBy { it.cost }
         if (goldBuilding != null) {
             val modifier = if (civInfo.statsForNextTurn.gold < 0) 3f else 1.2f
@@ -244,7 +248,7 @@ class ConstructionAutomation(val cityConstructions: CityConstructions){
     private fun addProductionBuildingChoice() {
         val hasWaterResource = cityInfo.tilesInRange
                 .any { it.isWater && it.resource!=null && it.position in cityInfo.tiles }
-        val productionBuilding = buildableNotWonders
+        val productionBuilding = buildableNotWonders.asSequence()
                 .filter { it.isStatRelated(Stat.Production)
                         || (hasWaterResource && (it.uniques.contains("+1 production and gold from all sea resources worked by the city")
                                                 || it.uniques.contains("+1 production from all sea resources worked by the city")) )
@@ -256,7 +260,7 @@ class ConstructionAutomation(val cityConstructions: CityConstructions){
     }
 
     private fun addFoodBuildingChoice() {
-        val foodBuilding = buildableNotWonders.filter { it.isStatRelated(Stat.Food)
+        val foodBuilding = buildableNotWonders.asSequence().filter { it.isStatRelated(Stat.Food)
                 || it.getBaseBuilding(civInfo.gameInfo.ruleSet).name == "Aqueduct" || it.getBaseBuilding(civInfo.gameInfo.ruleSet).name == "Medical Lab"}  // only stat related in unique
                 .minBy { it.cost }
         if (foodBuilding != null) {
diff --git a/core/src/com/unciv/logic/automation/SpecificUnitAutomation.kt b/core/src/com/unciv/logic/automation/SpecificUnitAutomation.kt
index 3da84501f5..6f42efb2b2 100644
--- a/core/src/com/unciv/logic/automation/SpecificUnitAutomation.kt
+++ b/core/src/com/unciv/logic/automation/SpecificUnitAutomation.kt
@@ -19,7 +19,7 @@ class SpecificUnitAutomation{
     }
 
     fun automateWorkBoats(unit: MapUnit) {
-        val seaResourcesInCities = unit.civInfo.cities.flatMap { city -> city.getWorkableTiles() }
+        val seaResourcesInCities = unit.civInfo.cities.asSequence().flatMap { city -> city.getWorkableTiles() }
                 .filter { hasWorkableSeaResource(it, unit.civInfo) && (unit.movement.canMoveTo(it) || unit.currentTile == it) }
         val closestReachableResource = seaResourcesInCities.sortedBy { it.arialDistanceTo(unit.currentTile) }
                 .firstOrNull { unit.movement.canReach(it) }
diff --git a/core/src/com/unciv/logic/city/CityConstructions.kt b/core/src/com/unciv/logic/city/CityConstructions.kt
index c44a1bf174..bb94d58633 100644
--- a/core/src/com/unciv/logic/city/CityConstructions.kt
+++ b/core/src/com/unciv/logic/city/CityConstructions.kt
@@ -6,8 +6,8 @@ import com.unciv.logic.automation.ConstructionAutomation
 import com.unciv.logic.civilization.AlertType
 import com.unciv.logic.civilization.PopupAlert
 import com.unciv.models.ruleset.Building
-import com.unciv.models.translations.tr
 import com.unciv.models.stats.Stats
+import com.unciv.models.translations.tr
 import com.unciv.ui.utils.withItem
 import com.unciv.ui.utils.withoutItem
 import java.util.*
@@ -33,11 +33,11 @@ class CityConstructions {
         return toReturn
     }
 
-    internal fun getBuildableBuildings(): List<Building> = cityInfo.getRuleset().buildings.values
-            .filter { it.isBuildable(this) }
+    internal fun getBuildableBuildings(): Sequence<Building> = cityInfo.getRuleset().buildings.values
+            .asSequence().filter { it.isBuildable(this) }
 
     fun getConstructableUnits() = cityInfo.getRuleset().units.values
-            .filter { it.isBuildable(this) }
+            .asSequence().filter { it.isBuildable(this) }
 
     fun getStats(): Stats {
         val stats = Stats()
@@ -109,7 +109,7 @@ class CityConstructions {
         throw NotBuildingOrUnitException("$constructionName is not a building or a unit!")
     }
 
-    internal fun getBuiltBuildings(): List<Building> = builtBuildingObjects
+    internal fun getBuiltBuildings(): Sequence<Building> = builtBuildingObjects.asSequence()
 
     fun containsBuildingOrEquivalent(building: String): Boolean =
             isBuilt(building) || getBuiltBuildings().any{it.replaces==building}
diff --git a/core/src/com/unciv/logic/city/CityInfo.kt b/core/src/com/unciv/logic/city/CityInfo.kt
index e2933096c2..7be3b0537f 100644
--- a/core/src/com/unciv/logic/city/CityInfo.kt
+++ b/core/src/com/unciv/logic/city/CityInfo.kt
@@ -116,7 +116,7 @@ class CityInfo {
 
 
     fun getCenterTile(): TileInfo = centerTileInfo
-    fun getTiles(): List<TileInfo> = tiles.map { tileMap[it] }
+    fun getTiles(): Sequence<TileInfo> = tiles.asSequence().map { tileMap[it] }
     fun getWorkableTiles() = getTiles().filter { it in tilesInRange }
 
     fun isCapital() = cityConstructions.isBuilt("Palace")
@@ -192,7 +192,7 @@ class CityInfo {
         return 0
     }
 
-    fun getBuildingUniques(): List<String> = cityConstructions.getBuiltBuildings().flatMap { it.uniques }
+    fun getBuildingUniques(): Sequence<String> = cityConstructions.getBuiltBuildings().flatMap { it.uniques.asSequence() }
     fun containsBuildingUnique(unique:String) = cityConstructions.getBuiltBuildings().any { it.uniques.contains(unique) }
 
     fun getGreatPersonMap():HashMap<String,Stats>{
diff --git a/core/src/com/unciv/logic/civilization/CivilizationInfo.kt b/core/src/com/unciv/logic/civilization/CivilizationInfo.kt
index 296a30aa5d..73b9dea146 100644
--- a/core/src/com/unciv/logic/civilization/CivilizationInfo.kt
+++ b/core/src/com/unciv/logic/civilization/CivilizationInfo.kt
@@ -492,7 +492,7 @@ class CivilizationInfo {
         val city = NextTurnAutomation().getClosestCities(this, otherCiv).city1
         val militaryUnit = city.cityConstructions.getConstructableUnits()
                 .filter { !it.unitType.isCivilian() && it.unitType.isLandUnit() }
-                .random()
+                .toList().random()
         placeUnitNearTile(city.location, militaryUnit.name)
         addNotification("[${otherCiv.civName}] gave us a [${militaryUnit.name}] as gift near [${city.name}]!", null, Color.GREEN)
     }