diff --git a/src/main/kotlin/ru/dbotthepony/kstarbound/Main.kt b/src/main/kotlin/ru/dbotthepony/kstarbound/Main.kt
index 6760bfbc..7ca2c686 100644
--- a/src/main/kotlin/ru/dbotthepony/kstarbound/Main.kt
+++ b/src/main/kotlin/ru/dbotthepony/kstarbound/Main.kt
@@ -4,7 +4,6 @@ import org.apache.logging.log4j.LogManager
 import org.lwjgl.Version
 import ru.dbotthepony.kstarbound.client.StarboundClient
 import ru.dbotthepony.kstarbound.server.IntegratedStarboundServer
-import ru.dbotthepony.kstarbound.util.random.random
 import java.io.File
 import java.net.InetSocketAddress
 
diff --git a/src/main/kotlin/ru/dbotthepony/kstarbound/Starbound.kt b/src/main/kotlin/ru/dbotthepony/kstarbound/Starbound.kt
index 17d71550..55443caa 100644
--- a/src/main/kotlin/ru/dbotthepony/kstarbound/Starbound.kt
+++ b/src/main/kotlin/ru/dbotthepony/kstarbound/Starbound.kt
@@ -151,6 +151,12 @@ object Starbound : BlockableEventLoop("Universe Thread"), Scheduler, ISBFileLoca
 	@JvmField
 	val COROUTINE_EXECUTOR = ExecutorWithScheduler(EXECUTOR, this).asCoroutineDispatcher()
 
+	// this is required for Caffeine since it ignores scheduler
+	// (and suffers noticeable throughput penalty) in rescheduleCleanUpIfIncomplete()
+	// if executor is specified as ForkJoinPool.commonPool()
+	@JvmField
+	val SCREENED_EXECUTOR: ExecutorService = object : ExecutorService by EXECUTOR {}
+
 	@JvmField
 	val CLEANER: Cleaner = Cleaner.create {
 		val t = Thread(it, "Starbound Global Cleaner")
diff --git a/src/main/kotlin/ru/dbotthepony/kstarbound/defs/image/Image.kt b/src/main/kotlin/ru/dbotthepony/kstarbound/defs/image/Image.kt
index c6a97f32..922e81d2 100644
--- a/src/main/kotlin/ru/dbotthepony/kstarbound/defs/image/Image.kt
+++ b/src/main/kotlin/ru/dbotthepony/kstarbound/defs/image/Image.kt
@@ -345,7 +345,7 @@ class Image private constructor(
 			.weigher<IStarboundFile, ByteBuffer> { key, value -> value.capacity() }
 			.maximumWeight((Runtime.getRuntime().maxMemory() / 4L).coerceIn(1_024L * 1_024L * 32L /* 32 МиБ */, 1_024L * 1_024L * 256L /* 256 МиБ */))
 			.scheduler(Starbound)
-			.executor(Starbound.EXECUTOR)
+			.executor(Starbound.EXECUTOR) // SCREENED_EXECUTOR shouldn't be used here
 			.buildAsync(CacheLoader {
 				readImageDirect(it).data
 			})
diff --git a/src/main/kotlin/ru/dbotthepony/kstarbound/defs/world/BiomePlaceables.kt b/src/main/kotlin/ru/dbotthepony/kstarbound/defs/world/BiomePlaceables.kt
index 2d30d667..78e2d953 100644
--- a/src/main/kotlin/ru/dbotthepony/kstarbound/defs/world/BiomePlaceables.kt
+++ b/src/main/kotlin/ru/dbotthepony/kstarbound/defs/world/BiomePlaceables.kt
@@ -228,7 +228,7 @@ data class BiomePlaceables(
 					return null // whut
 
 				if (staticRandomDouble(x, y, blockSeed) <= blockProbability) {
-					return Placement(randomItems[staticRandomInt(0, randomItems.size, x, y, blockSeed)], Vector2i(x, y), priority)
+					return Placement(randomItems[staticRandomInt(0, randomItems.size - 1, x, y, blockSeed)], Vector2i(x, y), priority)
 				}
 			} else {
 				if (weightedItems.isEmpty())
diff --git a/src/main/kotlin/ru/dbotthepony/kstarbound/defs/world/WorldTemplate.kt b/src/main/kotlin/ru/dbotthepony/kstarbound/defs/world/WorldTemplate.kt
index d8a59a06..84409b12 100644
--- a/src/main/kotlin/ru/dbotthepony/kstarbound/defs/world/WorldTemplate.kt
+++ b/src/main/kotlin/ru/dbotthepony/kstarbound/defs/world/WorldTemplate.kt
@@ -259,7 +259,7 @@ class WorldTemplate(val geometry: WorldGeometry) {
 				for (layer in worldParameters.layers) {
 					if (layer.dungeons.isNotEmpty()) {
 						val dungeonSpacing = geometry.size.x / layer.dungeons.size
-						var dungeonOffset = staticRandomInt(0, geometry.size.x, seed, layer.layerBaseHeight, "dungeon")
+						var dungeonOffset = staticRandomInt(0, geometry.size.x - 1, seed, layer.layerBaseHeight, "dungeon")
 
 						for (dungeon in layer.dungeons) {
 							if (dungeon.isPresent) {
@@ -303,7 +303,7 @@ class WorldTemplate(val geometry: WorldGeometry) {
 		.maximumSize(1_500_000L) // plentiful of space, and allows for high hit ratio (around 79%) in most situations
 		// downside is memory consumption, but why should it matter when we save 80% of cpu time?
 		.expireAfterAccess(Duration.ofSeconds(20))
-		.executor(Starbound.EXECUTOR)
+		.executor(Starbound.SCREENED_EXECUTOR)
 		.scheduler(Starbound)
 		// .recordStats()
 		.build<Vector2i, CellInfo> { (x, y) -> cellInfo0(x, y) }
diff --git a/src/main/kotlin/ru/dbotthepony/kstarbound/lua/bindings/AssetJsonFunction.kt b/src/main/kotlin/ru/dbotthepony/kstarbound/lua/bindings/AssetJsonFunction.kt
deleted file mode 100644
index f30bc682..00000000
--- a/src/main/kotlin/ru/dbotthepony/kstarbound/lua/bindings/AssetJsonFunction.kt
+++ /dev/null
@@ -1,27 +0,0 @@
-package ru.dbotthepony.kstarbound.lua.bindings
-
-import org.classdump.luna.ByteString
-import org.classdump.luna.LuaRuntimeException
-import org.classdump.luna.TableFactory
-import org.classdump.luna.impl.NonsuspendableFunctionException
-import org.classdump.luna.runtime.AbstractFunction1
-import org.classdump.luna.runtime.ExecutionContext
-import ru.dbotthepony.kstarbound.Starbound
-import ru.dbotthepony.kstarbound.lua.from
-
-class AssetJsonFunction(private val tables: TableFactory) : AbstractFunction1<ByteString>() {
-	override fun resume(context: ExecutionContext?, suspendedState: Any?) {
-		throw NonsuspendableFunctionException(this::class.java)
-	}
-
-	override fun invoke(context: ExecutionContext, arg1: ByteString?) {
-		arg1 ?: throw LuaRuntimeException("bad argument #1 to root.assetJson (string expected, got nil)")
-		val load = Starbound.loadJsonAsset(arg1.decode())
-
-		if (load == null) {
-			context.returnBuffer.setTo()
-		} else {
-			context.returnBuffer.setTo(tables.from(load))
-		}
-	}
-}
diff --git a/src/main/kotlin/ru/dbotthepony/kstarbound/lua/bindings/RootBindings.kt b/src/main/kotlin/ru/dbotthepony/kstarbound/lua/bindings/RootBindings.kt
index 702a74ca..635bc922 100644
--- a/src/main/kotlin/ru/dbotthepony/kstarbound/lua/bindings/RootBindings.kt
+++ b/src/main/kotlin/ru/dbotthepony/kstarbound/lua/bindings/RootBindings.kt
@@ -350,7 +350,10 @@ fun provideRootBindings(lua: LuaEnvironment) {
 	val table = lua.newTable()
 	lua.globals["root"] = table
 
-	table["assetJson"] = AssetJsonFunction(lua)
+	table["assetJson"] = luaFunction { path: ByteString ->
+		returnBuffer.setTo(from(Starbound.loadJsonAsset(path.decode())))
+	}
+
 	table["makeCurrentVersionedJson"] = luaStub("makeCurrentVersionedJson")
 	table["loadVersionedJson"] = luaStub("loadVersionedJson")
 
diff --git a/src/main/kotlin/ru/dbotthepony/kstarbound/lua/bindings/UtilityBindings.kt b/src/main/kotlin/ru/dbotthepony/kstarbound/lua/bindings/UtilityBindings.kt
index d5062be8..cba1a133 100644
--- a/src/main/kotlin/ru/dbotthepony/kstarbound/lua/bindings/UtilityBindings.kt
+++ b/src/main/kotlin/ru/dbotthepony/kstarbound/lua/bindings/UtilityBindings.kt
@@ -29,6 +29,7 @@ import ru.dbotthepony.kstarbound.util.random.staticRandomLong
 import ru.dbotthepony.kstarbound.util.toStarboundString
 import java.util.*
 import java.util.random.RandomGenerator
+import kotlin.math.sign
 
 private val LOGGER = LogManager.getLogger()
 
diff --git a/src/main/kotlin/ru/dbotthepony/kstarbound/lua/bindings/WorldBindings.kt b/src/main/kotlin/ru/dbotthepony/kstarbound/lua/bindings/WorldBindings.kt
index 52f3f930..2b8f9c6e 100644
--- a/src/main/kotlin/ru/dbotthepony/kstarbound/lua/bindings/WorldBindings.kt
+++ b/src/main/kotlin/ru/dbotthepony/kstarbound/lua/bindings/WorldBindings.kt
@@ -1,10 +1,12 @@
 package ru.dbotthepony.kstarbound.lua.bindings
 
 import org.classdump.luna.Table
+import org.classdump.luna.runtime.ExecutionContext
 import ru.dbotthepony.kstarbound.lua.LuaEnvironment
 import ru.dbotthepony.kstarbound.lua.get
 import ru.dbotthepony.kstarbound.lua.luaFunction
 import ru.dbotthepony.kstarbound.lua.set
+import ru.dbotthepony.kstarbound.lua.toPoly
 import ru.dbotthepony.kstarbound.lua.toVector2d
 import ru.dbotthepony.kstarbound.world.World
 
@@ -23,4 +25,8 @@ fun provideWorldBindings(self: World<*, *>, lua: LuaEnvironment) {
 			returnBuffer.setTo(self.geometry.diff(toVector2d(arg1), toVector2d(arg2)).length)
 		}
 	}
+
+	callbacks["polyContains"] = luaFunction { poly: Table, position: Table ->
+		returnBuffer.setTo(self.geometry.polyContains(toPoly(poly), toVector2d(position)))
+	}
 }
diff --git a/src/main/kotlin/ru/dbotthepony/kstarbound/server/world/ServerUniverse.kt b/src/main/kotlin/ru/dbotthepony/kstarbound/server/world/ServerUniverse.kt
index f1586207..ee3d9d49 100644
--- a/src/main/kotlin/ru/dbotthepony/kstarbound/server/world/ServerUniverse.kt
+++ b/src/main/kotlin/ru/dbotthepony/kstarbound/server/world/ServerUniverse.kt
@@ -221,7 +221,7 @@ class ServerUniverse private constructor(marker: Nothing?) : Universe(), Closeab
 		.maximumSize(1024L)
 		.softValues()
 		.scheduler(Starbound)
-		.executor(Starbound.EXECUTOR)
+		.executor(Starbound.SCREENED_EXECUTOR)
 		.build()
 
 	fun getChunkFuture(pos: Vector2i): CompletableFuture<KOptional<UniverseChunk>> {
diff --git a/src/main/kotlin/ru/dbotthepony/kstarbound/server/world/ServerWorldTracker.kt b/src/main/kotlin/ru/dbotthepony/kstarbound/server/world/ServerWorldTracker.kt
index b3fd7f31..066b7213 100644
--- a/src/main/kotlin/ru/dbotthepony/kstarbound/server/world/ServerWorldTracker.kt
+++ b/src/main/kotlin/ru/dbotthepony/kstarbound/server/world/ServerWorldTracker.kt
@@ -18,6 +18,7 @@ import ru.dbotthepony.kstarbound.client.network.packets.ChunkCellsPacket
 import ru.dbotthepony.kstarbound.defs.SpawnTarget
 import ru.dbotthepony.kstarbound.defs.WarpAction
 import ru.dbotthepony.kstarbound.defs.WorldID
+import ru.dbotthepony.kstarbound.defs.world.FlyingType
 import ru.dbotthepony.kstarbound.network.IPacket
 import ru.dbotthepony.kstarbound.network.packets.EntityCreatePacket
 import ru.dbotthepony.kstarbound.network.packets.EntityDestroyPacket
@@ -127,6 +128,8 @@ class ServerWorldTracker(val world: ServerWorld, val client: ServerConnection, p
 		}
 	}
 
+	private var lastSeenFlyingType = FlyingType.NONE
+
 	fun tick() {
 		if (!client.worldStartAcknowledged)
 			return
@@ -144,11 +147,12 @@ class ServerWorldTracker(val world: ServerWorld, val client: ServerConnection, p
 		}
 
 		run {
-			if (skyUpdateWaitTicks++ >= 20) {
+			if (skyUpdateWaitTicks++ >= 20 || world.sky.flyingType != lastSeenFlyingType) {
 				val (data, version) = world.sky.networkedGroup.write(skyVersion, isLegacy = client.isLegacy)
 				skyVersion = version
 				send(EnvironmentUpdatePacket(data, ByteArrayList()))
 				skyUpdateWaitTicks = 0
+				lastSeenFlyingType = world.sky.flyingType
 			}
 		}
 
diff --git a/src/main/kotlin/ru/dbotthepony/kstarbound/util/BlockableEventLoop.kt b/src/main/kotlin/ru/dbotthepony/kstarbound/util/BlockableEventLoop.kt
index bb2d8e96..7a0f967b 100644
--- a/src/main/kotlin/ru/dbotthepony/kstarbound/util/BlockableEventLoop.kt
+++ b/src/main/kotlin/ru/dbotthepony/kstarbound/util/BlockableEventLoop.kt
@@ -1,5 +1,6 @@
 package ru.dbotthepony.kstarbound.util
 
+import it.unimi.dsi.fastutil.objects.ObjectArrayList
 import kotlinx.coroutines.CancellationException
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.SupervisorJob
@@ -129,7 +130,7 @@ open class BlockableEventLoop(name: String) : Thread(name), ScheduledExecutorSer
 		}
 
 		if (scheduledQueue.isNotEmpty()) {
-			val executed = ArrayList<ScheduledTask<*>>()
+			val executed = ObjectArrayList<ScheduledTask<*>>(4)
 			var lastSize: Int
 
 			do {
diff --git a/src/main/kotlin/ru/dbotthepony/kstarbound/util/random/RandomUtils.kt b/src/main/kotlin/ru/dbotthepony/kstarbound/util/random/RandomUtils.kt
index a9d36006..5b041bd4 100644
--- a/src/main/kotlin/ru/dbotthepony/kstarbound/util/random/RandomUtils.kt
+++ b/src/main/kotlin/ru/dbotthepony/kstarbound/util/random/RandomUtils.kt
@@ -86,14 +86,14 @@ fun staticRandomDouble(vararg values: Any?): Double {
 	return staticRandom64(*values).ushr(11) * 1.1102230246251565E-16
 }
 
-fun staticRandomInt(origin: Int, bound: Int, vararg values: Any?): Int {
-	val rand = staticRandomDouble(*values)
-	return origin + ((bound - origin) * rand).toInt()
+fun staticRandomInt(min: Int, max: Int, vararg values: Any?): Int {
+	val hash = staticRandomDouble(*values)
+	return (min + (max - min + 1) * hash).toInt()
 }
 
-fun staticRandomLong(origin: Long, bound: Long, vararg values: Any?): Long {
-	val rand = staticRandomDouble(*values)
-	return origin + ((bound - origin) * rand).toLong()
+fun staticRandomLong(min: Long, max: Long, vararg values: Any?): Long {
+	val hash = staticRandomDouble(*values)
+	return (min + (max - min + 1L) * hash).toLong()
 }
 
 fun staticRandom64(vararg values: Any?): Long {
diff --git a/src/main/kotlin/ru/dbotthepony/kstarbound/world/Chunk.kt b/src/main/kotlin/ru/dbotthepony/kstarbound/world/Chunk.kt
index c5cfd299..1e8e1084 100644
--- a/src/main/kotlin/ru/dbotthepony/kstarbound/world/Chunk.kt
+++ b/src/main/kotlin/ru/dbotthepony/kstarbound/world/Chunk.kt
@@ -90,7 +90,7 @@ abstract class Chunk<WorldType : World<WorldType, This>, This : Chunk<WorldType,
 
 	// bulk mark collision dirty of neighbour chunks as well as ours
 	protected fun signalChunkContentsUpdated() {
-		val signalPositions = ArrayList<Vector2i>()
+		val signalPositions = ObjectArrayList<Vector2i>(24)
 
 		for (x in 1 .. 2) {
 			for (y in 1 .. 2) {
diff --git a/src/main/kotlin/ru/dbotthepony/kstarbound/world/Sky.kt b/src/main/kotlin/ru/dbotthepony/kstarbound/world/Sky.kt
index fd72eab2..d138bfd8 100644
--- a/src/main/kotlin/ru/dbotthepony/kstarbound/world/Sky.kt
+++ b/src/main/kotlin/ru/dbotthepony/kstarbound/world/Sky.kt
@@ -98,12 +98,18 @@ class Sky() {
 	}
 
 	fun startFlying(enterHyperspace: Boolean, startInWarp: Boolean = false) {
+		if (flyingType == FlyingType.NONE)
+			flyingTimer = 0.0
+		else if (flyingType == FlyingType.WARP && warpPhase == WarpPhase.SLOWING_DOWN) {
+			warpPhase = WarpPhase.SPEEDING_UP
+			flyingTimer = speedupTime
+		}
+
 		if (startInWarp)
 			flyingType = FlyingType.WARP
 		else if (flyingType == FlyingType.NONE)
 			flyingType = FlyingType.DISEMBARKING
 
-		// flyingTimer = 0.0
 		this.enterHyperspace = enterHyperspace
 		this.startInWarp = startInWarp
 	}
@@ -113,6 +119,11 @@ class Sky() {
 
 		if (skyType != SkyType.WARP)
 			skyType = SkyType.ORBITAL
+
+		if (flyingType == FlyingType.NONE || flyingType == FlyingType.ARRIVING) {
+			this.skyParameters = destination
+			this.destination = null
+		}
 	}
 
 	private var lastFlyingType = FlyingType.NONE
diff --git a/src/main/kotlin/ru/dbotthepony/kstarbound/world/WorldGeometry.kt b/src/main/kotlin/ru/dbotthepony/kstarbound/world/WorldGeometry.kt
index a34d51a2..d7112798 100644
--- a/src/main/kotlin/ru/dbotthepony/kstarbound/world/WorldGeometry.kt
+++ b/src/main/kotlin/ru/dbotthepony/kstarbound/world/WorldGeometry.kt
@@ -240,4 +240,13 @@ data class WorldGeometry(val size: Vector2i, val loopX: Boolean = true, val loop
 	fun polyDistance(poly: Poly, point: IStruct2d): Double {
 		return poly.distance(nearestTo(poly.centre, point))
 	}
+
+	fun split(poly: Poly): List<Poly> {
+		TODO()
+	}
+
+	fun polyContains(poly: Poly, point: IStruct2d): Boolean {
+		val wrap = wrap(point)
+		return split(poly).any { it.contains(wrap) }
+	}
 }
diff --git a/src/main/kotlin/ru/dbotthepony/kstarbound/world/terrain/KarstCaveTerrainSelector.kt b/src/main/kotlin/ru/dbotthepony/kstarbound/world/terrain/KarstCaveTerrainSelector.kt
index a8737cc5..c1e0ee01 100644
--- a/src/main/kotlin/ru/dbotthepony/kstarbound/world/terrain/KarstCaveTerrainSelector.kt
+++ b/src/main/kotlin/ru/dbotthepony/kstarbound/world/terrain/KarstCaveTerrainSelector.kt
@@ -62,7 +62,7 @@ class KarstCaveTerrainSelector(data: Data, parameters: TerrainSelectorParameters
 		.softValues()
 		.expireAfterAccess(Duration.ofMinutes(1))
 		.scheduler(Starbound)
-		.executor(Starbound.EXECUTOR)
+		.executor(Starbound.SCREENED_EXECUTOR)
 		.build<Int, Layer>(::Layer)
 
 	private inner class Sector(val sector: Vector2i) {
@@ -131,7 +131,7 @@ class KarstCaveTerrainSelector(data: Data, parameters: TerrainSelectorParameters
 		.softValues()
 		.expireAfterAccess(Duration.ofMinutes(1))
 		.scheduler(Starbound)
-		.executor(Starbound.EXECUTOR)
+		.executor(Starbound.SCREENED_EXECUTOR)
 		.build<Vector2i, Sector>(::Sector)
 
 	override fun get(x: Int, y: Int): Double {
diff --git a/src/main/kotlin/ru/dbotthepony/kstarbound/world/terrain/WormCaveTerrainSelector.kt b/src/main/kotlin/ru/dbotthepony/kstarbound/world/terrain/WormCaveTerrainSelector.kt
index 149c359d..6a3f60c5 100644
--- a/src/main/kotlin/ru/dbotthepony/kstarbound/world/terrain/WormCaveTerrainSelector.kt
+++ b/src/main/kotlin/ru/dbotthepony/kstarbound/world/terrain/WormCaveTerrainSelector.kt
@@ -185,7 +185,7 @@ class WormCaveTerrainSelector(data: Data, parameters: TerrainSelectorParameters)
 		.softValues()
 		.expireAfterAccess(Duration.ofMinutes(1))
 		.scheduler(Starbound)
-		.executor(Starbound.EXECUTOR)
+		.executor(Starbound.SCREENED_EXECUTOR)
 		.build<Vector2i, Sector>(::Sector)
 
 	override fun get(x: Int, y: Int): Double {