diff --git a/Libraries/LibWeb/DOM/CharacterData.cpp b/Libraries/LibWeb/DOM/CharacterData.cpp
index ceab2f30316..c88462121f2 100644
--- a/Libraries/LibWeb/DOM/CharacterData.cpp
+++ b/Libraries/LibWeb/DOM/CharacterData.cpp
@@ -126,7 +126,7 @@ WebIDL::ExceptionOr<void> CharacterData::replace_data(size_t offset, size_t coun
 
     // 12. If node’s parent is non-null, then run the children changed steps for node’s parent.
     if (parent())
-        parent()->children_changed();
+        parent()->children_changed(nullptr);
 
     // NOTE: Since the text node's data has changed, we need to invalidate the text for rendering.
     //       This ensures that the new text is reflected in layout, even if we don't end up
diff --git a/Libraries/LibWeb/DOM/Element.cpp b/Libraries/LibWeb/DOM/Element.cpp
index 3d1d2a07c8a..8d9850dc7e7 100644
--- a/Libraries/LibWeb/DOM/Element.cpp
+++ b/Libraries/LibWeb/DOM/Element.cpp
@@ -1107,9 +1107,9 @@ void Element::removed_from(Node* old_parent, Node& old_root)
         document().element_with_name_was_removed({}, *this);
 }
 
-void Element::children_changed()
+void Element::children_changed(ChildrenChangedMetadata const* metadata)
 {
-    Node::children_changed();
+    Node::children_changed(metadata);
     set_needs_style_update(true);
 }
 
diff --git a/Libraries/LibWeb/DOM/Element.h b/Libraries/LibWeb/DOM/Element.h
index 1679b4fee57..8c4a25bc525 100644
--- a/Libraries/LibWeb/DOM/Element.h
+++ b/Libraries/LibWeb/DOM/Element.h
@@ -420,7 +420,7 @@ protected:
 
     virtual void inserted() override;
     virtual void removed_from(Node* old_parent, Node& old_root) override;
-    virtual void children_changed() override;
+    virtual void children_changed(ChildrenChangedMetadata const*) override;
     virtual i32 default_tab_index_value() const;
 
     // https://dom.spec.whatwg.org/#concept-element-attributes-change-ext
diff --git a/Libraries/LibWeb/DOM/Node.cpp b/Libraries/LibWeb/DOM/Node.cpp
index 2ef0762e1ab..b5a624259d3 100644
--- a/Libraries/LibWeb/DOM/Node.cpp
+++ b/Libraries/LibWeb/DOM/Node.cpp
@@ -745,7 +745,8 @@ void Node::insert_before(GC::Ref<Node> node, GC::Ptr<Node> child, bool suppress_
     }
 
     // 9. Run the children changed steps for parent.
-    children_changed();
+    ChildrenChangedMetadata metadata { ChildrenChangedMetadata::Type::Inserted, node };
+    children_changed(&metadata);
 
     // 10. Let staticNodeList be a list of nodes, initially « ».
     // Spec-Note: We collect all nodes before calling the post-connection steps on any one of them, instead of calling
@@ -977,7 +978,7 @@ void Node::remove(bool suppress_observers)
     }
 
     // 21. Run the children changed steps for parent.
-    parent->children_changed();
+    parent->children_changed(nullptr);
 
     document().bump_dom_tree_version();
 }
diff --git a/Libraries/LibWeb/DOM/Node.h b/Libraries/LibWeb/DOM/Node.h
index 16213836dd8..b40df03731f 100644
--- a/Libraries/LibWeb/DOM/Node.h
+++ b/Libraries/LibWeb/DOM/Node.h
@@ -262,7 +262,18 @@ public:
     virtual void inserted();
     virtual void post_connection();
     virtual void removed_from(Node* old_parent, Node& old_root);
-    virtual void children_changed() { }
+    struct ChildrenChangedMetadata {
+        enum class Type {
+            Inserted,
+            Removal,
+            Mutation,
+        };
+        Type type {};
+        GC::Ref<Node> node;
+    };
+    // FIXME: It would be good if we could always provide this metadata for use in optimizations.
+    virtual void children_changed(ChildrenChangedMetadata const*) { }
+
     virtual void adopted_from(Document&) { }
     virtual WebIDL::ExceptionOr<void> cloned(Node&, bool) const { return {}; }
 
diff --git a/Libraries/LibWeb/HTML/HTMLDetailsElement.cpp b/Libraries/LibWeb/HTML/HTMLDetailsElement.cpp
index 46c91a21bad..1e7178ecd57 100644
--- a/Libraries/LibWeb/HTML/HTMLDetailsElement.cpp
+++ b/Libraries/LibWeb/HTML/HTMLDetailsElement.cpp
@@ -100,9 +100,9 @@ void HTMLDetailsElement::attribute_changed(FlyString const& local_name, Optional
     }
 }
 
-void HTMLDetailsElement::children_changed()
+void HTMLDetailsElement::children_changed(ChildrenChangedMetadata const* metadata)
 {
-    Base::children_changed();
+    Base::children_changed(metadata);
     update_shadow_tree_slots();
 }
 
diff --git a/Libraries/LibWeb/HTML/HTMLDetailsElement.h b/Libraries/LibWeb/HTML/HTMLDetailsElement.h
index 89d9d7d90a5..0e9ad921f5d 100644
--- a/Libraries/LibWeb/HTML/HTMLDetailsElement.h
+++ b/Libraries/LibWeb/HTML/HTMLDetailsElement.h
@@ -33,7 +33,7 @@ private:
 
     virtual void inserted() override;
     virtual void removed_from(DOM::Node* old_parent, DOM::Node& old_root) override;
-    virtual void children_changed() override;
+    virtual void children_changed(ChildrenChangedMetadata const*) override;
     virtual void attribute_changed(FlyString const& local_name, Optional<String> const& old_value, Optional<String> const& value, Optional<FlyString> const& namespace_) override;
 
     void queue_a_details_toggle_event_task(String old_state, String new_state);
diff --git a/Libraries/LibWeb/HTML/HTMLMediaElement.cpp b/Libraries/LibWeb/HTML/HTMLMediaElement.cpp
index 8444e37b3f6..298181e9170 100644
--- a/Libraries/LibWeb/HTML/HTMLMediaElement.cpp
+++ b/Libraries/LibWeb/HTML/HTMLMediaElement.cpp
@@ -766,9 +766,9 @@ private:
 
 GC_DEFINE_ALLOCATOR(SourceElementSelector);
 
-void HTMLMediaElement::children_changed()
+void HTMLMediaElement::children_changed(ChildrenChangedMetadata const* metadata)
 {
-    Base::children_changed();
+    Base::children_changed(metadata);
 
     if (m_source_element_selector)
         m_source_element_selector->process_next_candidate().release_value_but_fixme_should_propagate_errors();
diff --git a/Libraries/LibWeb/HTML/HTMLMediaElement.h b/Libraries/LibWeb/HTML/HTMLMediaElement.h
index 4805c7e60f7..c64d5cc7b31 100644
--- a/Libraries/LibWeb/HTML/HTMLMediaElement.h
+++ b/Libraries/LibWeb/HTML/HTMLMediaElement.h
@@ -158,7 +158,7 @@ protected:
 
     virtual void attribute_changed(FlyString const& name, Optional<String> const& old_value, Optional<String> const& value, Optional<FlyString> const& namespace_) override;
     virtual void removed_from(DOM::Node* old_parent, DOM::Node& old_root) override;
-    virtual void children_changed() override;
+    virtual void children_changed(ChildrenChangedMetadata const* metadata) override;
 
     // Override in subclasses to handle implementation-specific behavior when the element state changes
     // to playing or paused, e.g. to start/stop play timers.
diff --git a/Libraries/LibWeb/HTML/HTMLOptionElement.cpp b/Libraries/LibWeb/HTML/HTMLOptionElement.cpp
index 7d1da5a9b9e..e8dec0f8f5e 100644
--- a/Libraries/LibWeb/HTML/HTMLOptionElement.cpp
+++ b/Libraries/LibWeb/HTML/HTMLOptionElement.cpp
@@ -253,9 +253,9 @@ void HTMLOptionElement::removed_from(Node* old_parent, Node& old_root)
     }
 }
 
-void HTMLOptionElement::children_changed()
+void HTMLOptionElement::children_changed(ChildrenChangedMetadata const* metadata)
 {
-    Base::children_changed();
+    Base::children_changed(metadata);
 
     update_selection_label();
 }
diff --git a/Libraries/LibWeb/HTML/HTMLOptionElement.h b/Libraries/LibWeb/HTML/HTMLOptionElement.h
index ae0f1a56b8f..0fd4f76e6bb 100644
--- a/Libraries/LibWeb/HTML/HTMLOptionElement.h
+++ b/Libraries/LibWeb/HTML/HTMLOptionElement.h
@@ -55,7 +55,7 @@ private:
 
     virtual void inserted() override;
     virtual void removed_from(Node* old_parent, Node& old_root) override;
-    virtual void children_changed() override;
+    virtual void children_changed(ChildrenChangedMetadata const*) override;
 
     void ask_for_a_reset();
     void update_selection_label();
diff --git a/Libraries/LibWeb/HTML/HTMLScriptElement.cpp b/Libraries/LibWeb/HTML/HTMLScriptElement.cpp
index 32384801b2a..1c820564197 100644
--- a/Libraries/LibWeb/HTML/HTMLScriptElement.cpp
+++ b/Libraries/LibWeb/HTML/HTMLScriptElement.cpp
@@ -572,9 +572,9 @@ void HTMLScriptElement::prepare_script()
 }
 
 // https://html.spec.whatwg.org/multipage/scripting.html#script-processing-model:html-element-post-connection-steps-4
-void HTMLScriptElement::children_changed()
+void HTMLScriptElement::children_changed(ChildrenChangedMetadata const* metadata)
 {
-    Base::children_changed();
+    Base::children_changed(metadata);
 
     // 1. Run the script HTML element post-connection steps, given the script element.
     post_connection();
diff --git a/Libraries/LibWeb/HTML/HTMLScriptElement.h b/Libraries/LibWeb/HTML/HTMLScriptElement.h
index f652c51d5b2..7ab40492a38 100644
--- a/Libraries/LibWeb/HTML/HTMLScriptElement.h
+++ b/Libraries/LibWeb/HTML/HTMLScriptElement.h
@@ -43,7 +43,7 @@ public:
 
     bool is_parser_inserted() const { return !!m_parser_document; }
 
-    virtual void children_changed() override;
+    virtual void children_changed(ChildrenChangedMetadata const*) override;
     virtual void post_connection() override;
 
     // https://html.spec.whatwg.org/multipage/scripting.html#dom-script-supports
diff --git a/Libraries/LibWeb/HTML/HTMLSelectElement.cpp b/Libraries/LibWeb/HTML/HTMLSelectElement.cpp
index d7a6891738a..42070623503 100644
--- a/Libraries/LibWeb/HTML/HTMLSelectElement.cpp
+++ b/Libraries/LibWeb/HTML/HTMLSelectElement.cpp
@@ -292,9 +292,9 @@ i32 HTMLSelectElement::default_tab_index_value() const
     return 0;
 }
 
-void HTMLSelectElement::children_changed()
+void HTMLSelectElement::children_changed(ChildrenChangedMetadata const* metadata)
 {
-    Base::children_changed();
+    Base::children_changed(metadata);
     update_cached_list_of_options();
     update_selectedness();
 }
diff --git a/Libraries/LibWeb/HTML/HTMLSelectElement.h b/Libraries/LibWeb/HTML/HTMLSelectElement.h
index 7801e703f66..9f563200acf 100644
--- a/Libraries/LibWeb/HTML/HTMLSelectElement.h
+++ b/Libraries/LibWeb/HTML/HTMLSelectElement.h
@@ -109,7 +109,7 @@ private:
 
     virtual void computed_properties_changed() override;
 
-    virtual void children_changed() override;
+    virtual void children_changed(ChildrenChangedMetadata const*) override;
 
     void update_cached_list_of_options() const;
     void show_the_picker_if_applicable();
diff --git a/Libraries/LibWeb/HTML/HTMLStyleElement.cpp b/Libraries/LibWeb/HTML/HTMLStyleElement.cpp
index 4d8ec7b1926..2763b6e2c64 100644
--- a/Libraries/LibWeb/HTML/HTMLStyleElement.cpp
+++ b/Libraries/LibWeb/HTML/HTMLStyleElement.cpp
@@ -32,9 +32,9 @@ void HTMLStyleElement::visit_edges(Cell::Visitor& visitor)
     m_style_element_utils.visit_edges(visitor);
 }
 
-void HTMLStyleElement::children_changed()
+void HTMLStyleElement::children_changed(ChildrenChangedMetadata const* metadata)
 {
-    Base::children_changed();
+    Base::children_changed(metadata);
     m_style_element_utils.update_a_style_block(*this);
 }
 
diff --git a/Libraries/LibWeb/HTML/HTMLStyleElement.h b/Libraries/LibWeb/HTML/HTMLStyleElement.h
index e5bb976e3b9..314541ddcbe 100644
--- a/Libraries/LibWeb/HTML/HTMLStyleElement.h
+++ b/Libraries/LibWeb/HTML/HTMLStyleElement.h
@@ -19,7 +19,7 @@ class HTMLStyleElement final : public HTMLElement {
 public:
     virtual ~HTMLStyleElement() override;
 
-    virtual void children_changed() override;
+    virtual void children_changed(ChildrenChangedMetadata const*) override;
     virtual void inserted() override;
     virtual void removed_from(Node* old_parent, Node& old_root) override;
 
diff --git a/Libraries/LibWeb/HTML/HTMLTextAreaElement.cpp b/Libraries/LibWeb/HTML/HTMLTextAreaElement.cpp
index d4c5ba7ce87..d21f23f05d3 100644
--- a/Libraries/LibWeb/HTML/HTMLTextAreaElement.cpp
+++ b/Libraries/LibWeb/HTML/HTMLTextAreaElement.cpp
@@ -429,9 +429,9 @@ void HTMLTextAreaElement::update_placeholder_visibility()
 }
 
 // https://html.spec.whatwg.org/multipage/form-elements.html#the-textarea-element:children-changed-steps
-void HTMLTextAreaElement::children_changed()
+void HTMLTextAreaElement::children_changed(ChildrenChangedMetadata const* metadata)
 {
-    Base::children_changed();
+    Base::children_changed(metadata);
 
     // The children changed steps for textarea elements must, if the element's dirty value flag is false,
     // set the element's raw value to its child text content.
diff --git a/Libraries/LibWeb/HTML/HTMLTextAreaElement.h b/Libraries/LibWeb/HTML/HTMLTextAreaElement.h
index 19763895aa5..ca45cd7d24a 100644
--- a/Libraries/LibWeb/HTML/HTMLTextAreaElement.h
+++ b/Libraries/LibWeb/HTML/HTMLTextAreaElement.h
@@ -70,7 +70,7 @@ public:
     virtual void form_associated_element_was_removed(DOM::Node*) override;
     virtual void form_associated_element_attribute_changed(FlyString const&, Optional<String> const&, Optional<FlyString> const&) override;
 
-    virtual void children_changed() override;
+    virtual void children_changed(ChildrenChangedMetadata const*) override;
 
     // https://www.w3.org/TR/html-aria/#el-textarea
     virtual Optional<ARIA::Role> default_role() const override { return ARIA::Role::textbox; }
diff --git a/Libraries/LibWeb/HTML/HTMLTitleElement.cpp b/Libraries/LibWeb/HTML/HTMLTitleElement.cpp
index 0a7bc75f7e6..0cb33962c1b 100644
--- a/Libraries/LibWeb/HTML/HTMLTitleElement.cpp
+++ b/Libraries/LibWeb/HTML/HTMLTitleElement.cpp
@@ -27,9 +27,9 @@ void HTMLTitleElement::initialize(JS::Realm& realm)
     WEB_SET_PROTOTYPE_FOR_INTERFACE(HTMLTitleElement);
 }
 
-void HTMLTitleElement::children_changed()
+void HTMLTitleElement::children_changed(ChildrenChangedMetadata const* metadata)
 {
-    HTMLElement::children_changed();
+    HTMLElement::children_changed(metadata);
     auto navigable = this->navigable();
     if (navigable && navigable->is_traversable()) {
         navigable->traversable_navigable()->page().client().page_did_change_title(document().title().to_byte_string());
diff --git a/Libraries/LibWeb/HTML/HTMLTitleElement.h b/Libraries/LibWeb/HTML/HTMLTitleElement.h
index 25facd1cb62..b99cd99aae2 100644
--- a/Libraries/LibWeb/HTML/HTMLTitleElement.h
+++ b/Libraries/LibWeb/HTML/HTMLTitleElement.h
@@ -24,7 +24,7 @@ private:
     HTMLTitleElement(DOM::Document&, DOM::QualifiedName);
 
     virtual void initialize(JS::Realm&) override;
-    virtual void children_changed() override;
+    virtual void children_changed(ChildrenChangedMetadata const*) override;
 };
 
 }
diff --git a/Libraries/LibWeb/SVG/SVGElement.cpp b/Libraries/LibWeb/SVG/SVGElement.cpp
index cae35e520a9..45756e3b639 100644
--- a/Libraries/LibWeb/SVG/SVGElement.cpp
+++ b/Libraries/LibWeb/SVG/SVGElement.cpp
@@ -98,9 +98,9 @@ void SVGElement::inserted()
     update_use_elements_that_reference_this();
 }
 
-void SVGElement::children_changed()
+void SVGElement::children_changed(ChildrenChangedMetadata const* metadata)
 {
-    Base::children_changed();
+    Base::children_changed(metadata);
 
     update_use_elements_that_reference_this();
 }
diff --git a/Libraries/LibWeb/SVG/SVGElement.h b/Libraries/LibWeb/SVG/SVGElement.h
index 758969da1bc..c1c1615d525 100644
--- a/Libraries/LibWeb/SVG/SVGElement.h
+++ b/Libraries/LibWeb/SVG/SVGElement.h
@@ -36,7 +36,7 @@ protected:
 
     virtual void attribute_changed(FlyString const& name, Optional<String> const& old_value, Optional<String> const& value, Optional<FlyString> const& namespace_) override;
     virtual WebIDL::ExceptionOr<void> cloned(DOM::Node&, bool) const override;
-    virtual void children_changed() override;
+    virtual void children_changed(ChildrenChangedMetadata const*) override;
     virtual void inserted() override;
     virtual void removed_from(Node* old_parent, Node& old_root) override;
 
diff --git a/Libraries/LibWeb/SVG/SVGStyleElement.cpp b/Libraries/LibWeb/SVG/SVGStyleElement.cpp
index 081be93c5fc..0d33cd7caaf 100644
--- a/Libraries/LibWeb/SVG/SVGStyleElement.cpp
+++ b/Libraries/LibWeb/SVG/SVGStyleElement.cpp
@@ -30,9 +30,9 @@ void SVGStyleElement::visit_edges(Cell::Visitor& visitor)
     m_style_element_utils.visit_edges(visitor);
 }
 
-void SVGStyleElement::children_changed()
+void SVGStyleElement::children_changed(ChildrenChangedMetadata const* metadata)
 {
-    Base::children_changed();
+    Base::children_changed(metadata);
     m_style_element_utils.update_a_style_block(*this);
 }
 
diff --git a/Libraries/LibWeb/SVG/SVGStyleElement.h b/Libraries/LibWeb/SVG/SVGStyleElement.h
index c3043e89813..b6c925f7f7d 100644
--- a/Libraries/LibWeb/SVG/SVGStyleElement.h
+++ b/Libraries/LibWeb/SVG/SVGStyleElement.h
@@ -18,7 +18,7 @@ class SVGStyleElement final : public SVGElement {
 public:
     virtual ~SVGStyleElement() override;
 
-    virtual void children_changed() override;
+    virtual void children_changed(ChildrenChangedMetadata const*) override;
     virtual void inserted() override;
     virtual void removed_from(Node* old_parent, Node& old_root) override;
 
diff --git a/Libraries/LibWeb/SVG/SVGTitleElement.cpp b/Libraries/LibWeb/SVG/SVGTitleElement.cpp
index 7d3e5066f30..4569774c489 100644
--- a/Libraries/LibWeb/SVG/SVGTitleElement.cpp
+++ b/Libraries/LibWeb/SVG/SVGTitleElement.cpp
@@ -30,9 +30,9 @@ GC::Ptr<Layout::Node> SVGTitleElement::create_layout_node(GC::Ref<CSS::ComputedP
     return nullptr;
 }
 
-void SVGTitleElement::children_changed()
+void SVGTitleElement::children_changed(ChildrenChangedMetadata const* metadata)
 {
-    Base::children_changed();
+    Base::children_changed(metadata);
 
     auto& page = document().page();
     if (document().browsing_context() != &page.top_level_browsing_context())
diff --git a/Libraries/LibWeb/SVG/SVGTitleElement.h b/Libraries/LibWeb/SVG/SVGTitleElement.h
index a2cf46f2642..83f717cc0f6 100644
--- a/Libraries/LibWeb/SVG/SVGTitleElement.h
+++ b/Libraries/LibWeb/SVG/SVGTitleElement.h
@@ -20,7 +20,7 @@ private:
     virtual void initialize(JS::Realm&) override;
 
     virtual GC::Ptr<Layout::Node> create_layout_node(GC::Ref<CSS::ComputedProperties>) override;
-    virtual void children_changed() override;
+    virtual void children_changed(ChildrenChangedMetadata const*) override;
 };
 
 }