From 641c96e7d2046793615328610bec74b216a87f69 Mon Sep 17 00:00:00 2001
From: Ben Adams <thundercat@illyriad.co.uk>
Date: Sat, 21 Dec 2024 13:49:58 +0000
Subject: [PATCH] Allocate single byte keys once (#7952)

---
 src/Nethermind/Nethermind.Trie/PatriciaTree.cs | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/Nethermind/Nethermind.Trie/PatriciaTree.cs b/src/Nethermind/Nethermind.Trie/PatriciaTree.cs
index dfe0f01319f..3f17f845008 100644
--- a/src/Nethermind/Nethermind.Trie/PatriciaTree.cs
+++ b/src/Nethermind/Nethermind.Trie/PatriciaTree.cs
@@ -26,6 +26,8 @@ namespace Nethermind.Trie
     public class PatriciaTree
     {
         private const int MaxKeyStackAlloc = 64;
+        private readonly static byte[][] _singleByteKeys = [[0], [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15]];
+
         private readonly ILogger _logger;
 
         public const int OneNodeAvgMemoryEstimate = 384;
@@ -733,7 +735,7 @@ L X - - - - - - - - - - - - - - */
                             if (childNode.IsBranch)
                             {
                                 TrieNode extensionFromBranch =
-                                    TrieNodeFactory.CreateExtension(new[] { (byte)childNodeIndex }, childNode);
+                                    TrieNodeFactory.CreateExtension(_singleByteKeys[childNodeIndex], childNode);
                                 if (_logger.IsTrace)
                                     _logger.Trace(
                                         $"Extending child {childNodeIndex} {childNode} of {node} into {extensionFromBranch}");