Finish comment in ReactDOMComponentTree

src/renderers/dom/client/ReactDOMComponentTree.js

@@ -64,7 +64,10 @@ function uncacheNode(inst) {
  * node every time.
  *
  * Since we update `_renderedChildren` and the actual DOM at (slightly)
- * different times, we could race here and not get the
+ * different times, we could race here and see a newer `_renderedChildren` than
+ * the DOM nodes we see. To avoid this, ReactMultiChild calls
+ * `prepareToManageChildren` before we change `_renderedChildren`, at which
+ * time the container's child nodes are always cached (until it unmounts).
  */
 function precacheChildNodes(inst, node) {
   if (inst._flags & Flags.hasCachedChildNodes) {

src/renderers/dom/shared/ReactDOMComponent.js

@@ -1201,7 +1201,8 @@ assign(
     prepareToManageChildren: function() {
       // Before we add, remove, or reorder the children of a node, make sure
       // we have references to all of its children so we don't lose them, even
-      // if nefarious browser plugins add extra nodes to our tree.
+      // if nefarious browser plugins add extra nodes to our tree. This could be
+      // called once per child so it should be fast.
       ReactDOMComponentTree.precacheChildNodes(this, getNode(this));
     },
   }