diff --git a/src/main/kotlin/ru/dbotthepony/kstarbound/Starbound.kt b/src/main/kotlin/ru/dbotthepony/kstarbound/Starbound.kt
index a4f76c81..1dbb33b5 100644
--- a/src/main/kotlin/ru/dbotthepony/kstarbound/Starbound.kt
+++ b/src/main/kotlin/ru/dbotthepony/kstarbound/Starbound.kt
@@ -2,6 +2,8 @@ package ru.dbotthepony.kstarbound
 
 import com.google.gson.*
 import it.unimi.dsi.fastutil.ints.Int2ObjectAVLTreeMap
+import it.unimi.dsi.fastutil.ints.Int2ObjectOpenHashMap
+import it.unimi.dsi.fastutil.objects.Object2ObjectOpenHashMap
 import org.apache.logging.log4j.LogManager
 import ru.dbotthepony.kstarbound.api.IStarboundFile
 import ru.dbotthepony.kstarbound.api.NonExistingFile
@@ -30,7 +32,6 @@ import java.io.*
 import java.text.DateFormat
 import java.util.*
 import kotlin.collections.ArrayList
-import kotlin.collections.HashMap
 
 const val METRES_IN_STARBOUND_UNIT = 0.5
 const val METRES_IN_STARBOUND_UNITf = 0.5f
@@ -64,20 +65,20 @@ object Starbound {
 		return null
 	}
 
-	private val tiles = HashMap<String, TileDefinition>()
-	private val tilesByMaterialID = Int2ObjectAVLTreeMap<TileDefinition>()
+	private val tiles = Object2ObjectOpenHashMap<String, TileDefinition>()
+	private val tilesByMaterialID = Int2ObjectOpenHashMap<TileDefinition>()
 
-	private val tileModifiers = HashMap<String, MaterialModifier>()
-	private val tileModifiersByID = Int2ObjectAVLTreeMap<MaterialModifier>()
+	private val tileModifiers = Object2ObjectOpenHashMap<String, MaterialModifier>()
+	private val tileModifiersByID = Int2ObjectOpenHashMap<MaterialModifier>()
 
-	private val liquid = HashMap<String, LiquidDefinition>()
-	private val liquidByID = Int2ObjectAVLTreeMap<LiquidDefinition>()
+	private val liquid = Object2ObjectOpenHashMap<String, LiquidDefinition>()
+	private val liquidByID = Int2ObjectOpenHashMap<LiquidDefinition>()
 
-	private val projectiles = HashMap<String, ConfiguredProjectile>()
-	private val parallax = HashMap<String, ParallaxPrototype>()
-	private val functions = HashMap<String, JsonFunction>()
+	private val projectiles = Object2ObjectOpenHashMap<String, ConfiguredProjectile>()
+	private val parallax = Object2ObjectOpenHashMap<String, ParallaxPrototype>()
+	private val functions = Object2ObjectOpenHashMap<String, JsonFunction>()
 
-	private val items = HashMap<String, ItemDefinition>()
+	private val items = Object2ObjectOpenHashMap<String, ItemDefinition>()
 
 	val liquidAccess: Map<String, LiquidDefinition> = Collections.unmodifiableMap(liquid)
 	val liquidByIDAccess: Map<Int, LiquidDefinition> = Collections.unmodifiableMap(liquidByID)