diff --git a/src/main/kotlin/ru/dbotthepony/kstarbound/io/StarboundPak.kt b/src/main/kotlin/ru/dbotthepony/kstarbound/io/StarboundPak.kt
index 42b52af2..5523e366 100644
--- a/src/main/kotlin/ru/dbotthepony/kstarbound/io/StarboundPak.kt
+++ b/src/main/kotlin/ru/dbotthepony/kstarbound/io/StarboundPak.kt
@@ -1,7 +1,10 @@
 package ru.dbotthepony.kstarbound.io
 
+import it.unimi.dsi.fastutil.objects.Object2ObjectArrayMap
 import it.unimi.dsi.fastutil.objects.Object2ObjectFunction
 import it.unimi.dsi.fastutil.objects.Object2ObjectLinkedOpenHashMap
+import it.unimi.dsi.fastutil.objects.Object2ObjectMap
+import it.unimi.dsi.fastutil.objects.Object2ObjectMaps
 import ru.dbotthepony.kommons.gson.get
 import ru.dbotthepony.kommons.io.readBinaryString
 import ru.dbotthepony.kommons.io.readVarInt
@@ -48,10 +51,16 @@ class StarboundPak(val path: File, callback: (finished: Boolean, status: String)
 			get() = false
 
 		private var frozen = false
-		private val innerChildren = Object2ObjectLinkedOpenHashMap<String, IStarboundFile>()
+		private var innerChildren: Object2ObjectMap<String, IStarboundFile> = Object2ObjectArrayMap(2)
 
 		fun put(value: IStarboundFile) {
 			check(!frozen) { "Can't put, already frozen!" }
+
+			if (innerChildren is Object2ObjectArrayMap && innerChildren.size >= 8) {
+				innerChildren = Object2ObjectLinkedOpenHashMap(innerChildren)
+				children = Object2ObjectMaps.unmodifiable(innerChildren)
+			}
+
 			innerChildren[value.name] = value
 		}
 
@@ -61,7 +70,8 @@ class StarboundPak(val path: File, callback: (finished: Boolean, status: String)
 			return innerChildren.computeIfAbsent(name, Object2ObjectFunction { SBDirectory(it as String, this) }) as? SBDirectory ?: throw IllegalStateException("$name already exists (in ${computeFullPath()})")
 		}
 
-		override val children: Map<String, IStarboundFile> = Collections.unmodifiableMap(innerChildren)
+		override var children: Map<String, IStarboundFile> = Object2ObjectMaps.unmodifiable(innerChildren)
+			private set
 
 		fun freeze() {
 			check(!frozen) { "Already frozen" }