From d13774b881b297f2cd1a8d3193183d241dee625b Mon Sep 17 00:00:00 2001
From: Evan You <yyx990803@gmail.com>
Date: Wed, 21 Jul 2021 14:04:02 -0400
Subject: [PATCH] perf: skip patch on same vnode

---
 packages/runtime-core/src/renderer.ts | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/packages/runtime-core/src/renderer.ts b/packages/runtime-core/src/renderer.ts
index 4bf1f9038fe..99eaf02bb6f 100644
--- a/packages/runtime-core/src/renderer.ts
+++ b/packages/runtime-core/src/renderer.ts
@@ -470,6 +470,10 @@ function baseCreateRenderer(
     slotScopeIds = null,
     optimized = __DEV__ && isHmrUpdating ? false : !!n2.dynamicChildren
   ) => {
+    if (n1 === n2) {
+      return
+    }
+
     // patching & not same type, unmount old tree
     if (n1 && !isSameVNodeType(n1, n2)) {
       anchor = getNextHostNode(n1)
@@ -1152,8 +1156,12 @@ function baseCreateRenderer(
     const fragmentEndAnchor = (n2.anchor = n1 ? n1.anchor : hostCreateText(''))!
 
     let { patchFlag, dynamicChildren, slotScopeIds: fragmentSlotScopeIds } = n2
-    if (dynamicChildren) {
-      optimized = true
+
+    if (__DEV__ && isHmrUpdating) {
+      // HMR updated, force full diff
+      patchFlag = 0
+      optimized = false
+      dynamicChildren = null
     }
 
     // check if this is a slot fragment with :slotted scope ids
@@ -1163,13 +1171,6 @@ function baseCreateRenderer(
         : fragmentSlotScopeIds
     }
 
-    if (__DEV__ && isHmrUpdating) {
-      // HMR updated, force full diff
-      patchFlag = 0
-      optimized = false
-      dynamicChildren = null
-    }
-
     if (n1 == null) {
       hostInsert(fragmentStartAnchor, container, anchor)
       hostInsert(fragmentEndAnchor, container, anchor)