Also state the downside

src/main/kotlin/ru/dbotthepony/mc/otm/storage/API.kt

@@ -124,6 +124,7 @@ interface IStorageAcceptor<T : IStorageStack> : IStorage<T> {
  * two stacks match provided key.
  *
  * Technical decision of using [UUID]s for primary key for locating stacks is performance.
+ * The only downside is doubled memory usage for storing bidirectional map (implementation specific).
  * This allows us to avoid burden of constantly constructing keys out of stacks (e.g. [net.minecraft.world.item.ItemStack]s)
  * which may or may not produce performance hit; [UUID]s are lightweight, semantically not bound to anything and are
  * very good for distributed ID generation (so nothing in game has to be bound to one sequential number generator).