From 93f60a9461974011bf71b27cf9cdf54b0efc221a Mon Sep 17 00:00:00 2001
From: Tyler Boone <tboone@microsoft.com>
Date: Tue, 20 Aug 2019 13:08:04 -0700
Subject: [PATCH 1/2] improving performance of listing commits with a path

---
 LibGit2Sharp/Core/FileHistory.cs | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/LibGit2Sharp/Core/FileHistory.cs b/LibGit2Sharp/Core/FileHistory.cs
index 5c10a1a24..988a39cbb 100644
--- a/LibGit2Sharp/Core/FileHistory.cs
+++ b/LibGit2Sharp/Core/FileHistory.cs
@@ -163,6 +163,16 @@ private static void DetermineParentPaths(IRepository repo, Commit currentCommit,
 
         private static string ParentPath(IRepository repo, Commit currentCommit, string currentPath, Commit parentCommit)
         {
+            // optimization: if the SHA of the parent commit's TreeEntry is the same as this commit's TreeEntry then
+            // they are the same and there is no need to diff the commit
+            TreeEntry parentTreeEntry = parentCommit.Tree[currentPath];
+            TreeEntry thisTreeEntry = currentCommit.Tree[currentPath];
+            if (parentTreeEntry != null && parentTreeEntry.Target.Sha == thisTreeEntry.Target.Sha)
+            {
+                return currentPath;
+            }
+
+            // something in the tree is different, so we need to diff the commits to look for renames
             using (var treeChanges = repo.Diff.Compare<TreeChanges>(parentCommit.Tree, currentCommit.Tree))
             {
                 var treeEntryChanges = treeChanges.FirstOrDefault(c => c.Path == currentPath);

From d87e5041e0fc85c85d77739935807401fe1d6aad Mon Sep 17 00:00:00 2001
From: Tyler Boone <tboone@microsoft.com>
Date: Tue, 20 Aug 2019 13:08:37 -0700
Subject: [PATCH 2/2] caching TreeEntries to improve perfomance

---
 LibGit2Sharp/Tree.cs | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/LibGit2Sharp/Tree.cs b/LibGit2Sharp/Tree.cs
index ca7055183..8bcccea0b 100644
--- a/LibGit2Sharp/Tree.cs
+++ b/LibGit2Sharp/Tree.cs
@@ -39,6 +39,8 @@ internal Tree(Repository repo, ObjectId id, string path)
         /// </summary>
         public virtual int Count { get { return lazyCount.Value; } }
 
+        private Dictionary<string, TreeEntry> _treeCache;
+
         /// <summary>
         /// Gets the <see cref="TreeEntry"/> pointed at by the <paramref name="relativePath"/> in this <see cref="Tree"/> instance.
         /// </summary>
@@ -46,9 +48,19 @@ internal Tree(Repository repo, ObjectId id, string path)
         /// <returns><c>null</c> if nothing has been found, the <see cref="TreeEntry"/> otherwise.</returns>
         public virtual TreeEntry this[string relativePath]
         {
-            get { return RetrieveFromPath(relativePath); }
+            get
+            {
+                TreeEntry ret;
+                if (_treeCache == null) _treeCache = new Dictionary<string, TreeEntry>();
+                else if (_treeCache.TryGetValue(relativePath, out ret)) return ret;
+
+                ret = RetrieveFromPath(relativePath);
+                _treeCache[relativePath] = ret;
+                return ret;
+            }
         }
 
+
         private unsafe TreeEntry RetrieveFromPath(string relativePath)
         {
             if (string.IsNullOrEmpty(relativePath))