diff --git a/PKHeX.Core/Legality/Learnset/Learnset.cs b/PKHeX.Core/Legality/Learnset/Learnset.cs
index 4f021f5ba..88b29fe43 100644
--- a/PKHeX.Core/Legality/Learnset/Learnset.cs
+++ b/PKHeX.Core/Legality/Learnset/Learnset.cs
@@ -66,13 +66,23 @@ public int GetMinMoveLevel(int level)
             return Math.Max(end - 4, 1);
         }
 
+
+        private Dictionary<int, int> Learn;
+        private Dictionary<int, int> GetDictionary()
+        {
+            var dict = new Dictionary<int, int>();
+            for (int i = 0; i < Moves.Length; i++)
+                if (!dict.ContainsKey(Moves[i]))
+                    dict.Add(Moves[i], Levels[i]);
+            return dict;
+        }
+
         /// <summary>Returns the level that a Pokémon can learn the specified move.</summary>
         /// <param name="move">Move ID</param>
         /// <returns>Level the move is learned at. If the result is below 0, it cannot be learned by levelup.</returns>
         public int GetLevelLearnMove(int move)
         {
-            int index = Array.IndexOf(Moves, move);
-            return index < 0 ? index : Levels[index];
+            return (Learn ?? (Learn = GetDictionary())).TryGetValue(move, out var level) ? level : -1;
         }
     }
 }