diff --git a/PKHeX.Core/Saves/Encryption/MemeCrypto/MemeKey.cs b/PKHeX.Core/Saves/Encryption/MemeCrypto/MemeKey.cs
index 4e520f272..9bfd90c97 100644
--- a/PKHeX.Core/Saves/Encryption/MemeCrypto/MemeKey.cs
+++ b/PKHeX.Core/Saves/Encryption/MemeCrypto/MemeKey.cs
@@ -99,7 +99,7 @@ namespace PKHeX.Core
             // Well, (a ^ a) = 0. so (block first ^ subkey) ^ (block last ^ subkey)
             // = block first ^ block last ;)
             Array.Copy(outdata, ((data.Length / 0x10) - 1) * 0x10, temp, 0, 0x10);
-            temp = Xor(temp, outdata.Slice(0, 0x10));
+            temp = Xor(temp, outdata.AsSpan(0, 0x10));
             var subkey = GetSubKey(temp);
             for (var i = 0; i < data.Length / 0x10; i++)
             {
@@ -145,7 +145,7 @@ namespace PKHeX.Core
             }
 
             // In between - CMAC stuff
-            var inbet = outdata.Slice(0, 0x10);
+            var inbet = outdata.AsSpan(0, 0x10);
             temp = Xor(temp, inbet);
             var subkey = GetSubKey(temp);
 
@@ -183,7 +183,7 @@ namespace PKHeX.Core
             return subkey;
         }
 
-        private static byte[] Xor(byte[] b1, byte[] b2)
+        private static byte[] Xor(byte[] b1, ReadOnlySpan<byte> b2)
         {
             Debug.Assert(b1.Length == b2.Length);
             var x = new byte[b1.Length];
diff --git a/PKHeX.Core/Saves/Substructures/Gen5/CGearBackground.cs b/PKHeX.Core/Saves/Substructures/Gen5/CGearBackground.cs
index b96ba56e0..9c095dcb1 100644
--- a/PKHeX.Core/Saves/Substructures/Gen5/CGearBackground.cs
+++ b/PKHeX.Core/Saves/Substructures/Gen5/CGearBackground.cs
@@ -58,20 +58,18 @@ namespace PKHeX.Core
                 _cgb = data;
             }
 
-            byte[] Region1 = data.Slice(0, 0x1FE0);
-            byte[] ColorData = data.Slice(0x1FE0, 0x20);
-            byte[] Region2 = data.Slice(0x2000, 0x600);
+            var Region1 = data.AsSpan(0, 0x1FE0);
+            var ColorData = data.Slice(0x1FE0, 0x20);
+            var Region2 = data.Slice(0x2000, 0x600);
 
             ColorPalette = new int[ColorCount];
             for (int i = 0; i < ColorPalette.Length; i++)
                 ColorPalette[i] = GetRGB555_16(BitConverter.ToUInt16(ColorData, i * 2));
 
             Tiles = new Tile[0xFF];
-            for (int i = 0; i < 0xFF; i++)
+            for (int i = 0; i < Tiles.Length; i++)
             {
-                byte[] tiledata = new byte[Tile.SIZE_TILE];
-                Array.Copy(Region1, i * Tile.SIZE_TILE, tiledata, 0, Tile.SIZE_TILE);
-
+                byte[] tiledata = Region1.Slice(i * Tile.SIZE_TILE, Tile.SIZE_TILE).ToArray();
                 Tiles[i] = new Tile(tiledata);
                 Tiles[i].SetTile(ColorPalette);
             }
diff --git a/PKHeX.Core/Util/Util.cs b/PKHeX.Core/Util/Util.cs
index 5ed0ec7fb..8fea4b443 100644
--- a/PKHeX.Core/Util/Util.cs
+++ b/PKHeX.Core/Util/Util.cs
@@ -134,10 +134,10 @@ namespace PKHeX.Core
 
         public static string GetHexStringFromBytes(byte[] data, int offset, int length)
         {
-            data = data.Slice(offset, length);
-            var sb = new StringBuilder(data.Length * 2);
-            for (int i = data.Length - 1; i >= 0; i--)
-                sb.AppendFormat("{0:X2}", data[i]);
+            var arr = data.AsSpan(offset, length);
+            var sb = new StringBuilder(arr.Length * 2);
+            for (int i = arr.Length - 1; i >= 0; i--)
+                sb.AppendFormat("{0:X2}", arr[i]);
             return sb.ToString();
         }