diff --git a/src/record/observer.ts b/src/record/observer.ts
index c94aa735..3d6642cb 100644
--- a/src/record/observer.ts
+++ b/src/record/observer.ts
@@ -211,9 +211,11 @@ function initMutationObserver(
       });
     };
 
-    Array.from(movedSet).forEach(pushAdd);
+    for (var it = movedSet.values(), n = null; (n = it.next().value); ) {
+      pushAdd(n);
+    }
 
-    Array.from(addedSet).forEach(n => {
+    for (var it = addedSet.values(), n = null; (n = it.next().value); ) {
       if (!isAncestorInSet(droppedSet, n) && !isParentRemoved(removes, n)) {
         pushAdd(n);
       } else if (isAncestorInSet(movedSet, n)) {
@@ -221,7 +223,7 @@ function initMutationObserver(
       } else {
         droppedSet.add(n);
       }
-    });
+    }
 
     while (addQueue.length) {
       if (