diff --git a/core/tests/Drupal/KernelTests/Core/Extension/ModuleConfigureRouteTest.php b/core/tests/Drupal/KernelTests/Core/Extension/ModuleConfigureRouteTest.php
index b7e5a3f6d8e27cb32ebf98ca3834f15cec5a48d4..c4f6b02003a7bf45b8d8a5bb47f301ca38b4fd6a 100644
--- a/core/tests/Drupal/KernelTests/Core/Extension/ModuleConfigureRouteTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Extension/ModuleConfigureRouteTest.php
@@ -13,6 +13,7 @@
  *
  * @group #slow
  * @group Module
+ * @group #slow
  */
 class ModuleConfigureRouteTest extends KernelTestBase {
 
diff --git a/core/tests/Drupal/KernelTests/Core/Theme/Stable9LibraryOverrideTest.php b/core/tests/Drupal/KernelTests/Core/Theme/Stable9LibraryOverrideTest.php
index be6b1fc5342736589d1b01d2cddc255eecd61275..c0fd8c84e26e906766d81a260a1d45f5cd5ab128 100644
--- a/core/tests/Drupal/KernelTests/Core/Theme/Stable9LibraryOverrideTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Theme/Stable9LibraryOverrideTest.php
@@ -8,6 +8,7 @@
  * Tests Stable 9's library overrides.
  *
  * @group Theme
+ * @group #slow
  */
 class Stable9LibraryOverrideTest extends StableLibraryOverrideTestBase {