diff --git a/core/modules/settings_tray/tests/src/FunctionalJavascript/SettingsTrayBlockFormTest.php b/core/modules/settings_tray/tests/src/FunctionalJavascript/SettingsTrayBlockFormTest.php
index d505a0befcb3..a5db109f34c6 100644
--- a/core/modules/settings_tray/tests/src/FunctionalJavascript/SettingsTrayBlockFormTest.php
+++ b/core/modules/settings_tray/tests/src/FunctionalJavascript/SettingsTrayBlockFormTest.php
@@ -9,6 +9,7 @@ use Drupal\user\Entity\Role;
 /**
  * Testing opening and saving block forms in the off-canvas dialog.
  *
+ * @group #slow
  * @group settings_tray
  */
 class SettingsTrayBlockFormTest extends SettingsTrayTestBase {
diff --git a/core/modules/simpletest/tests/src/Functional/SimpletestUiTest.php b/core/modules/simpletest/tests/src/Functional/SimpletestUiTest.php
index 048ed2738949..f91cb6d5077d 100644
--- a/core/modules/simpletest/tests/src/Functional/SimpletestUiTest.php
+++ b/core/modules/simpletest/tests/src/Functional/SimpletestUiTest.php
@@ -10,6 +10,7 @@ use Drupal\Tests\BrowserTestBase;
 /**
  * Test various aspects of testing through the UI form.
  *
+ * @group #slow
  * @group simpletest
  */
 class SimpletestUiTest extends BrowserTestBase {
diff --git a/core/modules/system/tests/src/Functional/Module/InstallUninstallTest.php b/core/modules/system/tests/src/Functional/Module/InstallUninstallTest.php
index 9ca44078012f..d1f6be457f0d 100644
--- a/core/modules/system/tests/src/Functional/Module/InstallUninstallTest.php
+++ b/core/modules/system/tests/src/Functional/Module/InstallUninstallTest.php
@@ -9,6 +9,7 @@ use Drupal\workspaces\Entity\Workspace;
 /**
  * Install/uninstall core module and confirm table creation/deletion.
  *
+ * @group #slow
  * @group Module
  */
 class InstallUninstallTest extends ModuleTestBase {
diff --git a/core/modules/system/tests/src/Functional/Update/UpdatePathTestBaseFilledTest.php b/core/modules/system/tests/src/Functional/Update/UpdatePathTestBaseFilledTest.php
index 84b44df54791..5cc23b007d65 100644
--- a/core/modules/system/tests/src/Functional/Update/UpdatePathTestBaseFilledTest.php
+++ b/core/modules/system/tests/src/Functional/Update/UpdatePathTestBaseFilledTest.php
@@ -10,6 +10,7 @@ use Drupal\user\Entity\User;
 /**
  * Runs UpdatePathTestBaseTest with a dump filled with content.
  *
+ * @group #slow
  * @group Update
  * @group legacy
  */
diff --git a/core/modules/workspaces/tests/src/Kernel/WorkspaceIntegrationTest.php b/core/modules/workspaces/tests/src/Kernel/WorkspaceIntegrationTest.php
index 2678d899904c..160c0050575d 100644
--- a/core/modules/workspaces/tests/src/Kernel/WorkspaceIntegrationTest.php
+++ b/core/modules/workspaces/tests/src/Kernel/WorkspaceIntegrationTest.php
@@ -18,6 +18,7 @@ use Drupal\views\Views;
 /**
  * Tests a complete deployment scenario across different workspaces.
  *
+ * @group #slow
  * @group workspaces
  */
 class WorkspaceIntegrationTest extends KernelTestBase {
diff --git a/core/tests/Drupal/KernelTests/Core/Extension/ModuleConfigureRouteTest.php b/core/tests/Drupal/KernelTests/Core/Extension/ModuleConfigureRouteTest.php
index 96e469a84bbd..0fca6d2e6ecf 100644
--- a/core/tests/Drupal/KernelTests/Core/Extension/ModuleConfigureRouteTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Extension/ModuleConfigureRouteTest.php
@@ -8,6 +8,7 @@ use Drupal\KernelTests\KernelTestBase;
 /**
  * Tests the configure route for core modules.
  *
+ * @group #slow
  * @group Module
  */
 class ModuleConfigureRouteTest extends KernelTestBase {