Don't diff memoized host components

Author: gaearon

packages/react-reconciler/src/ReactFiberCompleteWork.js

@@ -361,6 +361,11 @@ function completeWork(
         // If we have an alternate, that means this is an update and we need to
         // schedule a side-effect to do the updates.
         const oldProps = current.memoizedProps;
+
+        if (oldProps === newProps) {
+          break;
+        }
+
         // If we get updated because one of our children updated, we don't
         // have newProps so we'll have to reuse them.
         // TODO: Split the update API as separate for the props vs. children.

packages/react-reconciler/src/__tests__/__snapshots__/ReactIncrementalPerf-test.internal.js.snap

@@ -85,8 +85,8 @@ exports[`ReactDebugFiberPerf deduplicates lifecycle names during commit to reduc
 
 ⚛ (Committing Changes)
   ⚛ (Committing Snapshot Effects: 0 Total)
-  ⚛ (Committing Host Effects: 3 Total)
-  ⚛ (Calling Lifecycle Methods: 3 Total)
+  ⚛ (Committing Host Effects: 2 Total)
+  ⚛ (Calling Lifecycle Methods: 2 Total)
     ⚛ B.componentDidUpdate
 "
 `;
@@ -257,8 +257,8 @@ exports[`ReactDebugFiberPerf measures deprioritized work 1`] = `
 
 ⚛ (Committing Changes)
   ⚛ (Committing Snapshot Effects: 0 Total)
-  ⚛ (Committing Host Effects: 3 Total)
-  ⚛ (Calling Lifecycle Methods: 2 Total)
+  ⚛ (Committing Host Effects: 1 Total)
+  ⚛ (Calling Lifecycle Methods: 0 Total)
 "
 `;
 
@@ -311,8 +311,8 @@ exports[`ReactDebugFiberPerf recovers from caught errors 1`] = `
 
 ⚛ (Committing Changes)
   ⚛ (Committing Snapshot Effects: 0 Total)
-  ⚛ (Committing Host Effects: 2 Total)
-  ⚛ (Calling Lifecycle Methods: 1 Total)
+  ⚛ (Committing Host Effects: 1 Total)
+  ⚛ (Calling Lifecycle Methods: 0 Total)
 "
 `;
 
@@ -357,8 +357,8 @@ exports[`ReactDebugFiberPerf skips parents during setState 1`] = `
 
 ⚛ (Committing Changes)
   ⚛ (Committing Snapshot Effects: 0 Total)
-  ⚛ (Committing Host Effects: 6 Total)
-  ⚛ (Calling Lifecycle Methods: 6 Total)
+  ⚛ (Committing Host Effects: 2 Total)
+  ⚛ (Calling Lifecycle Methods: 2 Total)
 "
 `;
 
@@ -431,8 +431,8 @@ exports[`ReactDebugFiberPerf warns on cascading renders from setState 1`] = `
 
 ⚛ (Committing Changes)
   ⚛ (Committing Snapshot Effects: 0 Total)
-  ⚛ (Committing Host Effects: 2 Total)
-  ⚛ (Calling Lifecycle Methods: 2 Total)
+  ⚛ (Committing Host Effects: 1 Total)
+  ⚛ (Calling Lifecycle Methods: 1 Total)
 "
 `;