One high-stakes, no-holds-barred, to-the-death profiling later, and we're left with a much less laggy main screen and a much more profile-able citybutton/

core/src/com/unciv/ui/map/TileGroupMap.kt

@@ -1,5 +1,6 @@
 package com.unciv.ui.map
 
+import com.badlogic.gdx.graphics.g2d.Batch
 import com.badlogic.gdx.math.Vector2
 import com.badlogic.gdx.scenes.scene2d.Group
 import com.unciv.logic.HexMath
@@ -71,4 +72,10 @@ class TileGroupMap<T: TileGroup>(val tileGroups: Collection<T>, val padding: Flo
                 .sub(groupSize.toFloat() / 2f, groupSize.toFloat() / 2f)
                 .scl(1f / trueGroupSize)
     }
+
+
+    // For debugging purposes
+    override fun draw(batch: Batch?, parentAlpha: Float) {
+        super.draw(batch, parentAlpha)
+    }
 }

core/src/com/unciv/ui/tilegroups/CityButton.kt

@@ -1,6 +1,7 @@
 package com.unciv.ui.tilegroups
 
 import com.badlogic.gdx.graphics.Color
+import com.badlogic.gdx.graphics.g2d.Batch
 import com.badlogic.gdx.math.Interpolation
 import com.badlogic.gdx.scenes.scene2d.Actor
 import com.badlogic.gdx.scenes.scene2d.Group
@@ -178,7 +179,10 @@ class CityButton(val city: CityInfo, private val tileGroup: WorldTileGroup): Tab
 
     private fun getIconTable(): Table {
         val secondaryColor = city.civInfo.nation.getInnerColor()
-        val iconTable = Table()
+        class IconTable:Table(){
+            override fun draw(batch: Batch?, parentAlpha: Float) { super.draw(batch, parentAlpha) }
+        }
+        val iconTable = IconTable()
         iconTable.touchable=Touchable.enabled
         iconTable.background = ImageGetter.getRoundedEdgeTableBackground(city.civInfo.nation.getOuterColor())
 
@@ -256,9 +260,13 @@ class CityButton(val city: CityInfo, private val tileGroup: WorldTileGroup): Tab
     private fun getPopulationGroup(showGrowth: Boolean): Group {
         val growthGreen = Color(0.0f, 0.5f, 0.0f, 1.0f)
 
-        val group = Group()
 
-        val populationLabel = city.population.population.toString().toLabel()
+        class PopulationGroup:Group() { // for recognition in the profiler
+            override fun draw(batch: Batch?, parentAlpha: Float) { super.draw(batch, parentAlpha) }
+        }
+        val group = PopulationGroup().apply { isTransform=false }
+
+        val populationLabel = city.population.population.toLabel()
         populationLabel.color = city.civInfo.nation.getInnerColor()
 
         group.addActor(populationLabel)
@@ -288,31 +296,13 @@ class CityButton(val city: CityInfo, private val tileGroup: WorldTileGroup): Tab
             when {
                 city.isGrowing() -> {
                     val turnsToGrowth = city.getNumTurnsToNewPopulation()
-                    turnLabel = if (turnsToGrowth != null) {
+                    turnLabel = if (turnsToGrowth != null && turnsToGrowth < 100) turnsToGrowth.toString().toLabel() else "∞".toLabel()
-                        if (turnsToGrowth < 100) {
-                            turnsToGrowth.toString().toLabel()
-                        } else {
-                            "∞".toLabel()
-                        }
-                    } else {
-                        "∞".toLabel()
-                    }
                 }
                 city.isStarving() -> {
                     val turnsToStarvation = city.getNumTurnsToStarvation()
-                    turnLabel = if (turnsToStarvation != null) {
+                    turnLabel = if (turnsToStarvation != null && turnsToStarvation < 100) turnsToStarvation.toString().toLabel() else "∞".toLabel()
-                        if (turnsToStarvation < 100) {
-                            turnsToStarvation.toString().toLabel()
-                        } else {
-                            "∞".toLabel()
-                        }
-                    } else {
-                        "∞".toLabel()
-                    }
-                }
-                else -> {
-                    turnLabel = "∞".toLabel()
                 }
+                else -> turnLabel = "∞".toLabel()
             }
             turnLabel.color = city.civInfo.nation.getInnerColor()
             turnLabel.setFontSize(14)
@@ -329,7 +319,14 @@ class CityButton(val city: CityInfo, private val tileGroup: WorldTileGroup): Tab
 
     private fun getConstructionGroup(cityConstructions: CityConstructions): Group {
         val cityCurrentConstruction = cityConstructions.getCurrentConstruction()
-        val group= Group()
+
+        class ConstructionGroup : Group() { // for recognition in the profiler
+            override fun draw(batch: Batch?, parentAlpha: Float) {
+                super.draw(batch, parentAlpha)
+            }
+        }
+
+        val group = ConstructionGroup().apply { isTransform = false }
         val groupHeight = 25f
         val groupWidth = if (cityCurrentConstruction is PerpetualConstruction) 15f else 40f
         group.setSize(groupWidth, groupHeight)
@@ -412,7 +409,10 @@ class CityButton(val city: CityInfo, private val tileGroup: WorldTileGroup): Tab
                 return barPiece
             }
 
-            val influenceBar = Table().apply {
+            class InfluenceTable:Table() { // for recognition in the profiler
+                override fun draw(batch: Batch?, parentAlpha: Float) { super.draw(batch, parentAlpha) }
+            }
+            val influenceBar = InfluenceTable().apply {
                 defaults().pad(1f)
                 setSize(width, height)
                 background = ImageGetter.getBackground(Color.BLACK)
@@ -425,4 +425,9 @@ class CityButton(val city: CityInfo, private val tileGroup: WorldTileGroup): Tab
         }
     }
 
+    // For debugging purposes
+    override fun draw(batch: Batch?, parentAlpha: Float) {
+        super.draw(batch, parentAlpha)
+    }
+
 }

core/src/com/unciv/ui/tilegroups/TileGroup.kt

@@ -1,6 +1,7 @@
 package com.unciv.ui.tilegroups
 
 import com.badlogic.gdx.graphics.Color
+import com.badlogic.gdx.graphics.g2d.Batch
 import com.badlogic.gdx.scenes.scene2d.Actor
 import com.badlogic.gdx.scenes.scene2d.Group
 import com.badlogic.gdx.scenes.scene2d.Touchable
@@ -31,7 +32,11 @@ open class TileGroup(var tileInfo: TileInfo, var tileSetStrings:TileSetStrings)
     Circle, Crosshair, Fog layer
     City name
      */
-    val baseLayerGroup = Group().apply { isTransform = false; setSize(groupSize, groupSize) }
+
+    // For recognizing the group in the profiler
+    class BaseLayerGroupClass:Group()
+    val baseLayerGroup = BaseLayerGroupClass().apply { isTransform = false; setSize(groupSize, groupSize)  }
+
     protected var tileBaseImages: ArrayList<Image> = ArrayList()
     /** List of ;-delimited image locations comprising the layers -
      * for instance, "desert+flood plains" might have an improvment for which there is a certain image eg "desert+flood plains+farm"
@@ -43,8 +48,9 @@ open class TileGroup(var tileInfo: TileInfo, var tileSetStrings:TileSetStrings)
     protected var baseTerrainOverlayImage: Image? = null
     protected var baseTerrain: String = ""
 
-
+    class TerrainFeatureLayerGroupClass:Group()
-    val terrainFeatureLayerGroup = Group().apply { isTransform = false; setSize(groupSize, groupSize) }
+    val terrainFeatureLayerGroup = TerrainFeatureLayerGroupClass()
+            .apply { isTransform = false; setSize(groupSize, groupSize) }
 
     // These are for OLD tiles - for instance the "forest" symbol on the forest
     protected var terrainFeatureOverlayImage: Image? = null
@@ -57,7 +63,9 @@ open class TileGroup(var tileInfo: TileInfo, var tileSetStrings:TileSetStrings)
     protected var pixelCivilianUnitImageLocation = ""
     protected var pixelCivilianUnitGroup = Group().apply { isTransform = false; setSize(groupSize, groupSize) }
 
-    val miscLayerGroup = Group().apply { isTransform = false; setSize(groupSize, groupSize) }
+    class MiscLayerGroupClass:Group()
+    val miscLayerGroup = MiscLayerGroupClass().apply { isTransform = false; setSize(groupSize, groupSize) }
+
     var resourceImage: Actor? = null
     var resource: String? = null
     private val roadImages = HashMap<TileInfo, RoadImage>()
@@ -65,7 +73,8 @@ open class TileGroup(var tileInfo: TileInfo, var tileSetStrings:TileSetStrings)
 
     val icons = TileGroupIcons(this)
 
-    val unitLayerGroup = Group().apply { isTransform = false; setSize(groupSize, groupSize);touchable = Touchable.disabled }
+    class UnitLayerGroupClass:Group()
+    val unitLayerGroup = UnitLayerGroupClass().apply { isTransform = false; setSize(groupSize, groupSize);touchable = Touchable.disabled }
 
     val cityButtonLayerGroup = Group().apply { isTransform = true; setSize(groupSize, groupSize);
         touchable = Touchable.childrenOnly; setOrigin(Align.center) }
@@ -162,7 +171,6 @@ open class TileGroup(var tileInfo: TileInfo, var tileSetStrings:TileSetStrings)
             if (ImageGetter.imageExists(terrainAndCity))
                 return listOf(terrainAndCity)
 
-//            val cityWithEra = tileSetStrings.getCityTile()
             if (ImageGetter.imageExists(tileSetStrings.cityTile))
                 return listOf(tileSetStrings.cityTile)
         }
@@ -677,4 +685,9 @@ open class TileGroup(var tileInfo: TileInfo, var tileSetStrings:TileSetStrings)
     fun hideCircle() {
         circleImage.isVisible = false
     }
+
+    /** This exists so we can easily find the TileGroup draw method in the android profiling, otherwise it's just a mass of Group.draw->drawChildren->Group.draw etc. */
+    override fun draw(batch: Batch?, parentAlpha: Float) {
+        super.draw(batch, parentAlpha)
+    }
 }

core/src/com/unciv/ui/tilegroups/WorldTileGroup.kt

@@ -1,5 +1,6 @@
 package com.unciv.ui.tilegroups
 
+import com.badlogic.gdx.graphics.g2d.Batch
 import com.unciv.UncivGame
 import com.unciv.logic.city.CityInfo
 import com.unciv.logic.civilization.CivilizationInfo
@@ -61,4 +62,5 @@ class WorldTileGroup(internal val worldScreen: WorldScreen, tileInfo: TileInfo,
         if (city == null) return false
         return worldScreen.bottomUnitTable.citySelected(city)
     }
+
 }

core/src/com/unciv/ui/worldscreen/Minimap.kt

@@ -1,6 +1,7 @@
 package com.unciv.ui.worldscreen
 
 import com.badlogic.gdx.graphics.Color
+import com.badlogic.gdx.graphics.g2d.Batch
 import com.badlogic.gdx.math.Vector2
 import com.badlogic.gdx.scenes.scene2d.Group
 import com.badlogic.gdx.scenes.scene2d.ui.Image
@@ -161,4 +162,10 @@ class MinimapHolder(mapHolder: WorldMapHolder): Table(){
         isVisible = UncivGame.Current.settings.showMinimap
         minimap.update(civInfo)
     }
+
+
+    // For debugging purposes
+    override fun draw(batch: Batch?, parentAlpha: Float) {
+        super.draw(batch, parentAlpha)
+    }
 }

core/src/com/unciv/ui/worldscreen/WorldMapHolder.kt

@@ -3,6 +3,7 @@ package com.unciv.ui.worldscreen
 import com.badlogic.gdx.Gdx
 import com.badlogic.gdx.Input
 import com.badlogic.gdx.graphics.Color
+import com.badlogic.gdx.graphics.g2d.Batch
 import com.badlogic.gdx.math.Interpolation
 import com.badlogic.gdx.math.Vector2
 import com.badlogic.gdx.scenes.scene2d.*
@@ -445,4 +446,9 @@ class WorldMapHolder(internal val worldScreen: WorldScreen, internal val tileMap
         for(tileGroup in tileGroups.values)
             tileGroup.cityButtonLayerGroup.setScale(scale)
     }
+
+    // For debugging purposes
+    override fun draw(batch: Batch?, parentAlpha: Float) {
+        super.draw(batch, parentAlpha)
+    }
 }

desktop/src/com/unciv/app/desktop/DesktopLauncher.kt

@@ -118,8 +118,19 @@ internal object DesktopLauncher {
         // Apparently some chipsets, like NVIDIA Tegra 3 graphics chipset (used in Asus TF700T tablet),
         // don't support non-power-of-two texture sizes - kudos @yuroller!
         // https://github.com/yairm210/UnCiv/issues/1340
-        settings.maxWidth = 2048
+
-        settings.maxHeight = 2048
+        /**
+         * These should be as big as possible in order to accommodate ALL the images together in one bug file.
+         * Why? Because the rendering function of the main screen renders all the images consecutively, and every time it needs to switch between textures,
+         * this causes a delay, leading to horrible lag if there are enough switches.
+         * The cost of this specific solution is that the entire game.png needs be be kept in-memory constantly.
+         * It's currently only 1.5MB so it should be okay, but it' an important point to remember for the future.
+         * Sidenode: Modded tilesets don't have this problem, since all the images are included in the mod's single PNG.
+         * Probably. Unless they have some truly huge images.
+         */
+        settings.maxWidth = 4096
+        settings.maxHeight = 4096
+
         settings.combineSubdirectories = true
         settings.pot = true
         settings.fast = true