diff --git a/Userland/Libraries/LibWeb/DOM/Document.h b/Userland/Libraries/LibWeb/DOM/Document.h
index 6e40c04f54..40e8e454a4 100644
--- a/Userland/Libraries/LibWeb/DOM/Document.h
+++ b/Userland/Libraries/LibWeb/DOM/Document.h
@@ -387,6 +387,9 @@ public:
     void set_parser(Badge<HTML::HTMLParser>, HTML::HTMLParser&);
     void detach_parser(Badge<HTML::HTMLParser>);
 
+    void set_is_temporary_document_for_fragment_parsing(Badge<HTML::HTMLParser>) { m_temporary_document_for_fragment_parsing = true; }
+    [[nodiscard]] bool is_temporary_document_for_fragment_parsing() const { return m_temporary_document_for_fragment_parsing; }
+
     static bool is_valid_name(DeprecatedString const&);
 
     struct PrefixAndTagName {
@@ -688,6 +691,8 @@ private:
     bool m_will_declaratively_refresh { false };
 
     RefPtr<Core::Timer> m_active_refresh_timer;
+
+    bool m_temporary_document_for_fragment_parsing { false };
 };
 
 template<>
diff --git a/Userland/Libraries/LibWeb/DOM/StyleElementUtils.cpp b/Userland/Libraries/LibWeb/DOM/StyleElementUtils.cpp
index 743977d4ef..de71d98ff4 100644
--- a/Userland/Libraries/LibWeb/DOM/StyleElementUtils.cpp
+++ b/Userland/Libraries/LibWeb/DOM/StyleElementUtils.cpp
@@ -23,6 +23,11 @@ namespace Web::DOM {
 // https://html.spec.whatwg.org/multipage/semantics.html#update-a-style-block
 void StyleElementUtils::update_a_style_block(DOM::Element& style_element)
 {
+    // OPTIMIZATION: Skip parsing CSS if we're in the middle of parsing a HTML fragment.
+    //               The style block will be parsed upon insertion into a proper document.
+    if (style_element.document().is_temporary_document_for_fragment_parsing())
+        return;
+
     // 1. Let element be the style element.
     // 2. If element has an associated CSS style sheet, remove the CSS style sheet in question.
 
diff --git a/Userland/Libraries/LibWeb/HTML/Parser/HTMLParser.cpp b/Userland/Libraries/LibWeb/HTML/Parser/HTMLParser.cpp
index 822738d3b9..876a40c881 100644
--- a/Userland/Libraries/LibWeb/HTML/Parser/HTMLParser.cpp
+++ b/Userland/Libraries/LibWeb/HTML/Parser/HTMLParser.cpp
@@ -3665,6 +3665,8 @@ Vector<JS::Handle<DOM::Node>> HTMLParser::parse_html_fragment(DOM::Element& cont
     auto temp_document = DOM::Document::create(context_element.realm()).release_value_but_fixme_should_propagate_errors();
     temp_document->set_document_type(DOM::Document::Type::HTML);
 
+    temp_document->set_is_temporary_document_for_fragment_parsing({});
+
     // 2. If the node document of the context element is in quirks mode, then let the Document be in quirks mode.
     //    Otherwise, the node document of the context element is in limited-quirks mode, then let the Document be in limited-quirks mode.
     //    Otherwise, leave the Document in no-quirks mode.