diff --git a/server-timing/class-perflab-server-timing-metric.php b/includes/server-timing/class-perflab-server-timing-metric.php
similarity index 100%
rename from server-timing/class-perflab-server-timing-metric.php
rename to includes/server-timing/class-perflab-server-timing-metric.php
diff --git a/server-timing/class-perflab-server-timing.php b/includes/server-timing/class-perflab-server-timing.php
similarity index 100%
rename from server-timing/class-perflab-server-timing.php
rename to includes/server-timing/class-perflab-server-timing.php
diff --git a/server-timing/defaults.php b/includes/server-timing/defaults.php
similarity index 100%
rename from server-timing/defaults.php
rename to includes/server-timing/defaults.php
diff --git a/server-timing/load.php b/includes/server-timing/load.php
similarity index 100%
rename from server-timing/load.php
rename to includes/server-timing/load.php
diff --git a/server-timing/object-cache.copy.php b/includes/server-timing/object-cache.copy.php
similarity index 84%
rename from server-timing/object-cache.copy.php
rename to includes/server-timing/object-cache.copy.php
index 7bd961b802..319483d375 100644
--- a/server-timing/object-cache.copy.php
+++ b/includes/server-timing/object-cache.copy.php
@@ -3,7 +3,7 @@
  * Plugin Name: Performance Lab Server Timing Object Cache Drop-In
  * Plugin URI: https://github.com/WordPress/performance
  * Description: Performance Lab drop-in to register Server-Timing metrics early. This is not a real object cache drop-in and will not override other actual object cache drop-ins.
- * Version: 2
+ * Version: 3
  * Author: WordPress Performance Team
  * Author URI: https://make.wordpress.org/performance/
  * License: GPLv2 or later
@@ -34,7 +34,7 @@
 
 // Set constant to be able to later check for whether this file was loaded.
 if ( ! defined( 'PERFLAB_OBJECT_CACHE_DROPIN_VERSION' ) ) {
-	define( 'PERFLAB_OBJECT_CACHE_DROPIN_VERSION', 2 );
+	define( 'PERFLAB_OBJECT_CACHE_DROPIN_VERSION', 3 );
 }
 
 if ( ! function_exists( 'perflab_load_server_timing_api_from_dropin' ) ) {
@@ -58,17 +58,17 @@ function perflab_load_server_timing_api_from_dropin() {
 
 		$plugins_dir = defined( 'WP_PLUGIN_DIR' ) ? WP_PLUGIN_DIR : WP_CONTENT_DIR . '/plugins';
 		$plugin_dir  = $plugins_dir . '/performance-lab/';
-		if ( ! file_exists( $plugin_dir . 'server-timing/load.php' ) ) {
+		if ( ! file_exists( $plugin_dir . 'includes/server-timing/load.php' ) ) {
 			$plugin_dir = $plugins_dir . '/performance/';
-			if ( ! file_exists( $plugin_dir . 'server-timing/load.php' ) ) {
+			if ( ! file_exists( $plugin_dir . 'includes/server-timing/load.php' ) ) {
 				return;
 			}
 		}
 
-		require_once $plugin_dir . 'server-timing/class-perflab-server-timing-metric.php';
-		require_once $plugin_dir . 'server-timing/class-perflab-server-timing.php';
-		require_once $plugin_dir . 'server-timing/load.php';
-		require_once $plugin_dir . 'server-timing/defaults.php';
+		require_once $plugin_dir . 'includes/server-timing/class-perflab-server-timing-metric.php';
+		require_once $plugin_dir . 'includes/server-timing/class-perflab-server-timing.php';
+		require_once $plugin_dir . 'includes/server-timing/load.php';
+		require_once $plugin_dir . 'includes/server-timing/defaults.php';
 	}
 }
 perflab_load_server_timing_api_from_dropin();
diff --git a/modules/database/audit-autoloaded-options/helper.php b/includes/site-health/audit-autoloaded-options/helper.php
similarity index 100%
rename from modules/database/audit-autoloaded-options/helper.php
rename to includes/site-health/audit-autoloaded-options/helper.php
diff --git a/modules/database/audit-autoloaded-options/hooks.php b/includes/site-health/audit-autoloaded-options/hooks.php
similarity index 100%
rename from modules/database/audit-autoloaded-options/hooks.php
rename to includes/site-health/audit-autoloaded-options/hooks.php
diff --git a/modules/js-and-css/audit-enqueued-assets/helper.php b/includes/site-health/audit-enqueued-assets/helper.php
similarity index 100%
rename from modules/js-and-css/audit-enqueued-assets/helper.php
rename to includes/site-health/audit-enqueued-assets/helper.php
diff --git a/modules/js-and-css/audit-enqueued-assets/hooks.php b/includes/site-health/audit-enqueued-assets/hooks.php
similarity index 100%
rename from modules/js-and-css/audit-enqueued-assets/hooks.php
rename to includes/site-health/audit-enqueued-assets/hooks.php
diff --git a/includes/site-health/load.php b/includes/site-health/load.php
new file mode 100644
index 0000000000..8cf164b302
--- /dev/null
+++ b/includes/site-health/load.php
@@ -0,0 +1,23 @@
+<?php
+/**
+ * Site Health checks loader.
+ *
+ * @package performance-lab
+ * @since n.e.x.t
+ */
+
+if ( ! defined( 'ABSPATH' ) ) {
+	exit; // Exit if accessed directly.
+}
+
+// Audit Autoloaded Options site health check.
+require_once __DIR__ . '/audit-autoloaded-options/helper.php';
+require_once __DIR__ . '/audit-autoloaded-options/hooks.php';
+
+// Audit Enqueued Assets site health check.
+require_once __DIR__ . '/audit-enqueued-assets/helper.php';
+require_once __DIR__ . '/audit-enqueued-assets/hooks.php';
+
+// WebP Support site health check.
+require_once __DIR__ . '/webp-support/helper.php';
+require_once __DIR__ . '/webp-support/hooks.php';
diff --git a/modules/images/webp-support/helper.php b/includes/site-health/webp-support/helper.php
similarity index 100%
rename from modules/images/webp-support/helper.php
rename to includes/site-health/webp-support/helper.php
diff --git a/modules/images/webp-support/hooks.php b/includes/site-health/webp-support/hooks.php
similarity index 100%
rename from modules/images/webp-support/hooks.php
rename to includes/site-health/webp-support/hooks.php
diff --git a/load.php b/load.php
index f8c6069c28..cf38b07c0c 100644
--- a/load.php
+++ b/load.php
@@ -30,10 +30,14 @@
 	define( 'PERFLAB_OBJECT_CACHE_DROPIN_VERSION', false );
 }
 
-require_once PERFLAB_PLUGIN_DIR_PATH . 'server-timing/class-perflab-server-timing-metric.php';
-require_once PERFLAB_PLUGIN_DIR_PATH . 'server-timing/class-perflab-server-timing.php';
-require_once PERFLAB_PLUGIN_DIR_PATH . 'server-timing/load.php';
-require_once PERFLAB_PLUGIN_DIR_PATH . 'server-timing/defaults.php';
+// Load server-timing API.
+require_once PERFLAB_PLUGIN_DIR_PATH . 'includes/server-timing/class-perflab-server-timing-metric.php';
+require_once PERFLAB_PLUGIN_DIR_PATH . 'includes/server-timing/class-perflab-server-timing.php';
+require_once PERFLAB_PLUGIN_DIR_PATH . 'includes/server-timing/load.php';
+require_once PERFLAB_PLUGIN_DIR_PATH . 'includes/server-timing/defaults.php';
+
+// Load site health checks.
+require_once PERFLAB_PLUGIN_DIR_PATH . 'includes/site-health/load.php';
 
 /**
  * Registers the performance modules setting.
@@ -122,22 +126,7 @@ function perflab_get_module_settings() {
 	// Even though a default value is registered for this setting, the default must be explicitly
 	// passed here, to support scenarios where this function is called before the 'init' action,
 	// for example when loading the active modules.
-	$module_settings = (array) get_option( PERFLAB_MODULES_SETTING, perflab_get_modules_setting_default() );
-
-	$legacy_module_slugs = array(
-		'site-health/audit-autoloaded-options' => 'database/audit-autoloaded-options',
-		'site-health/audit-enqueued-assets'    => 'js-and-css/audit-enqueued-assets',
-		'site-health/webp-support'             => 'images/webp-support',
-	);
-
-	foreach ( $legacy_module_slugs as $legacy_slug => $current_slug ) {
-		if ( isset( $module_settings[ $legacy_slug ] ) ) {
-			$module_settings[ $current_slug ] = $module_settings[ $legacy_slug ];
-			unset( $module_settings[ $legacy_slug ] );
-		}
-	}
-
-	return $module_settings;
+	return (array) get_option( PERFLAB_MODULES_SETTING, perflab_get_modules_setting_default() );
 }
 
 /**
@@ -424,7 +413,7 @@ function perflab_maybe_set_object_cache_dropin() {
 			return;
 		}
 
-		$wp_filesystem->copy( PERFLAB_PLUGIN_DIR_PATH . 'server-timing/object-cache.copy.php', $dropin_path );
+		$wp_filesystem->copy( PERFLAB_PLUGIN_DIR_PATH . 'includes/server-timing/object-cache.copy.php', $dropin_path );
 	}
 
 	// Set timeout of 1 hour before retrying again (only relevant in case the above failed).
diff --git a/modules/database/audit-autoloaded-options/can-load.php b/modules/database/audit-autoloaded-options/can-load.php
deleted file mode 100644
index 274a266348..0000000000
--- a/modules/database/audit-autoloaded-options/can-load.php
+++ /dev/null
@@ -1,19 +0,0 @@
-<?php
-/**
- * Can load function to determine if Site Health module is supported or not.
- *
- * @since   2.8.0
- * @package performance-lab
- */
-
-if ( ! defined( 'ABSPATH' ) ) {
-	exit; // Exit if accessed directly.
-}
-
-return static function () {
-	if ( ! has_filter( 'user_has_cap', 'wp_maybe_grant_site_health_caps' ) ) {
-		return new WP_Error( 'cannot_load_module', esc_html__( 'The module cannot be loaded since the Site Health feature is disabled.', 'performance-lab' ) );
-	} else {
-		return true;
-	}
-};
diff --git a/modules/database/audit-autoloaded-options/load.php b/modules/database/audit-autoloaded-options/load.php
deleted file mode 100644
index f8834b9ba7..0000000000
--- a/modules/database/audit-autoloaded-options/load.php
+++ /dev/null
@@ -1,17 +0,0 @@
-<?php
-/**
- * Module Name: Autoloaded Options Health Check
- * Description: Adds a check for autoloaded options in Site Health status.
- * Experimental: Yes
- *
- * @package performance-lab
- * @since 1.0.0
- */
-
-// Do not load the code if it is already loaded through another means.
-if ( function_exists( 'perflab_aao_add_autoloaded_options_test' ) ) {
-	return;
-}
-
-require_once __DIR__ . '/helper.php';
-require_once __DIR__ . '/hooks.php';
diff --git a/modules/images/webp-support/can-load.php b/modules/images/webp-support/can-load.php
deleted file mode 100644
index 274a266348..0000000000
--- a/modules/images/webp-support/can-load.php
+++ /dev/null
@@ -1,19 +0,0 @@
-<?php
-/**
- * Can load function to determine if Site Health module is supported or not.
- *
- * @since   2.8.0
- * @package performance-lab
- */
-
-if ( ! defined( 'ABSPATH' ) ) {
-	exit; // Exit if accessed directly.
-}
-
-return static function () {
-	if ( ! has_filter( 'user_has_cap', 'wp_maybe_grant_site_health_caps' ) ) {
-		return new WP_Error( 'cannot_load_module', esc_html__( 'The module cannot be loaded since the Site Health feature is disabled.', 'performance-lab' ) );
-	} else {
-		return true;
-	}
-};
diff --git a/modules/images/webp-support/load.php b/modules/images/webp-support/load.php
deleted file mode 100644
index 65f2df7aa7..0000000000
--- a/modules/images/webp-support/load.php
+++ /dev/null
@@ -1,17 +0,0 @@
-<?php
-/**
- * Module Name: WebP Support Health Check
- * Description: Adds a WebP support check in Site Health status.
- * Experimental: No
- *
- * @package performance-lab
- * @since 1.0.0
- */
-
-// Do not load the code if it is already loaded through another means.
-if ( function_exists( 'webp_uploads_add_is_webp_supported_test' ) ) {
-	return;
-}
-
-require_once __DIR__ . '/helper.php';
-require_once __DIR__ . '/hooks.php';
diff --git a/modules/js-and-css/audit-enqueued-assets/can-load.php b/modules/js-and-css/audit-enqueued-assets/can-load.php
deleted file mode 100644
index 274a266348..0000000000
--- a/modules/js-and-css/audit-enqueued-assets/can-load.php
+++ /dev/null
@@ -1,19 +0,0 @@
-<?php
-/**
- * Can load function to determine if Site Health module is supported or not.
- *
- * @since   2.8.0
- * @package performance-lab
- */
-
-if ( ! defined( 'ABSPATH' ) ) {
-	exit; // Exit if accessed directly.
-}
-
-return static function () {
-	if ( ! has_filter( 'user_has_cap', 'wp_maybe_grant_site_health_caps' ) ) {
-		return new WP_Error( 'cannot_load_module', esc_html__( 'The module cannot be loaded since the Site Health feature is disabled.', 'performance-lab' ) );
-	} else {
-		return true;
-	}
-};
diff --git a/modules/js-and-css/audit-enqueued-assets/load.php b/modules/js-and-css/audit-enqueued-assets/load.php
deleted file mode 100644
index 3a644a2b31..0000000000
--- a/modules/js-and-css/audit-enqueued-assets/load.php
+++ /dev/null
@@ -1,17 +0,0 @@
-<?php
-/**
- * Module Name: Enqueued Assets Health Check
- * Description: Adds a CSS and JS resource check in Site Health status.
- * Experimental: Yes
- *
- * @package performance-lab
- * @since 1.0.0
- */
-
-// Do not load the code if it is already loaded through another means.
-if ( function_exists( 'perflab_aea_audit_enqueued_scripts' ) ) {
-	return;
-}
-
-require_once __DIR__ . '/helper.php';
-require_once __DIR__ . '/hooks.php';
diff --git a/phpcs.xml.dist b/phpcs.xml.dist
index 0c8967890a..042f680152 100644
--- a/phpcs.xml.dist
+++ b/phpcs.xml.dist
@@ -12,7 +12,7 @@
 	</rule>
 
 	<rule ref="WordPress.Files.FileName.NotHyphenatedLowercase">
-		<exclude-pattern>server-timing/object-cache.copy.php</exclude-pattern>
+		<exclude-pattern>includes/server-timing/object-cache.copy.php</exclude-pattern>
 	</rule>
 
 	<file>.</file>
diff --git a/phpstan.neon.dist b/phpstan.neon.dist
index 618e13ca19..55eff44c9d 100644
--- a/phpstan.neon.dist
+++ b/phpstan.neon.dist
@@ -7,9 +7,8 @@ parameters:
 		- default-enabled-modules.php
 		- load.php
 		- module-i18n.php
-		- modules/
+		- includes/
 		- plugins/
-		- server-timing/
 		- tests/
 		- uninstall.php
 	scanDirectories:
diff --git a/tests/server-timing/load-tests.php b/tests/includes/server-timing/load-tests.php
similarity index 100%
rename from tests/server-timing/load-tests.php
rename to tests/includes/server-timing/load-tests.php
diff --git a/tests/server-timing/perflab-server-timing-metric-tests.php b/tests/includes/server-timing/perflab-server-timing-metric-tests.php
similarity index 100%
rename from tests/server-timing/perflab-server-timing-metric-tests.php
rename to tests/includes/server-timing/perflab-server-timing-metric-tests.php
diff --git a/tests/server-timing/perflab-server-timing-tests.php b/tests/includes/server-timing/perflab-server-timing-tests.php
similarity index 100%
rename from tests/server-timing/perflab-server-timing-tests.php
rename to tests/includes/server-timing/perflab-server-timing-tests.php
diff --git a/tests/modules/database/audit-autoloaded-options/audit-autoloaded-options-test.php b/tests/includes/site-health/audit-autoloaded-options/audit-autoloaded-options-test.php
similarity index 100%
rename from tests/modules/database/audit-autoloaded-options/audit-autoloaded-options-test.php
rename to tests/includes/site-health/audit-autoloaded-options/audit-autoloaded-options-test.php
diff --git a/tests/modules/js-and-css/audit-enqueued-assets/audit-enqueued-assets-helper-test.php b/tests/includes/site-health/audit-enqueued-assets/audit-enqueued-assets-helper-test.php
similarity index 100%
rename from tests/modules/js-and-css/audit-enqueued-assets/audit-enqueued-assets-helper-test.php
rename to tests/includes/site-health/audit-enqueued-assets/audit-enqueued-assets-helper-test.php
diff --git a/tests/modules/js-and-css/audit-enqueued-assets/audit-enqueued-assets-test.php b/tests/includes/site-health/audit-enqueued-assets/audit-enqueued-assets-test.php
similarity index 100%
rename from tests/modules/js-and-css/audit-enqueued-assets/audit-enqueued-assets-test.php
rename to tests/includes/site-health/audit-enqueued-assets/audit-enqueued-assets-test.php
diff --git a/tests/load-tests.php b/tests/load-tests.php
index 825fa09bd5..4eef28e58b 100644
--- a/tests/load-tests.php
+++ b/tests/load-tests.php
@@ -97,36 +97,6 @@ static function ( $current_default, $option, $passed_default ) use ( &$has_passe
 		$this->assertEqualSetsWithIndex( $new_value, $settings );
 	}
 
-	/**
-	 * @dataProvider data_legacy_modules
-	 */
-	public function test_legacy_module_for_perflab_get_module_settings( $legacy_module_slug, $current_module_slug ) {
-		$new_value = array( $legacy_module_slug => array( 'enabled' => true ) );
-		update_option( PERFLAB_MODULES_SETTING, $new_value );
-
-		$settings = perflab_get_module_settings();
-		$this->assertArrayNotHasKey( $legacy_module_slug, $settings, 'The settings do not contain the old legacy module slug in the database' );
-		$this->assertArrayHasKey( $current_module_slug, $settings, 'The settings contain an updated module slug in the database' );
-	}
-
-	/**
-	 * Data provider for test_legacy_module_for_perflab_get_module_settings().
-	 *
-	 * @return array {
-	 *     @type array {
-	 *         @type string $legacy_module_slug  The legacy module slug.
-	 *         @type string $current_module_slug The new/updated module slug.
-	 *     }
-	 * }
-	 */
-	public function data_legacy_modules() {
-		return array(
-			array( 'site-health/audit-autoloaded-options', 'database/audit-autoloaded-options' ),
-			array( 'site-health/audit-enqueued-assets', 'js-and-css/audit-enqueued-assets' ),
-			array( 'site-health/webp-support', 'images/webp-support' ),
-		);
-	}
-
 	public function test_perflab_get_active_modules() {
 		// Assert that by default there are no active modules.
 		$active_modules          = perflab_get_active_modules();
@@ -181,45 +151,6 @@ public function test_perflab_render_generator() {
 		$this->assertStringContainsString( $expected, $output );
 	}
 
-	/**
-	 * @dataProvider data_perflab_can_load_module
-	 */
-	public function test_perflab_is_valid_module( $dummy_module, $expected_status ) {
-		$this->assertSame( $expected_status, perflab_is_valid_module( $dummy_module ) );
-	}
-
-	public function data_perflab_is_valid_module() {
-		return array(
-			array( '', false ),
-			array( '../tests/testdata/demo-modules/something/non-existing-module', false ),
-			array( '../tests/testdata/demo-modules/js-and-css/demo-module-1', false ),
-			array( '../tests/testdata/demo-modules/something/demo-module-2', true ),
-			array( '../tests/testdata/demo-modules/images/demo-module-3', true ),
-			array( '../tests/testdata/demo-modules/check-error/demo-module-4', false ),
-		);
-	}
-
-	/**
-	 * @dataProvider data_perflab_can_load_module
-	 */
-	public function test_perflab_can_load_module( $dummy_module, $expected_status ) {
-		$this->assertSame( $expected_status, perflab_can_load_module( $dummy_module ) );
-	}
-
-	public function data_perflab_can_load_module() {
-		return array(
-			array( '../tests/testdata/demo-modules/js-and-css/demo-module-1', false ),
-			array( '../tests/testdata/demo-modules/something/demo-module-2', true ),
-			array( '../tests/testdata/demo-modules/images/demo-module-3', true ),
-		);
-	}
-
-	public function test_perflab_can_load_module_with_not_loaded_module() {
-		$can_load_module = perflab_can_load_module( '../tests/testdata/demo-modules/check-error/demo-module-4' );
-		$this->assertInstanceOf( 'WP_Error', $can_load_module );
-		$this->assertSame( 'cannot_load_module', $can_load_module->get_error_code() );
-	}
-
 	public function test_perflab_activate_module() {
 		perflab_activate_module( __DIR__ . '/testdata/demo-modules/something/demo-module-2' );
 		$this->assertSame( 'activated', get_option( 'test_demo_module_activation_status' ) );
@@ -230,19 +161,6 @@ public function test_perflab_deactivate_module() {
 		$this->assertSame( 'deactivated', get_option( 'test_demo_module_activation_status' ) );
 	}
 
-	private function get_expected_default_option() {
-		// This code is essentially copied over from the perflab_register_modules_setting() function.
-		$default_enabled_modules = require PERFLAB_PLUGIN_DIR_PATH . 'default-enabled-modules.php';
-		return array_reduce(
-			$default_enabled_modules,
-			static function ( $module_settings, $module_dir ) {
-				$module_settings[ $module_dir ] = array( 'enabled' => true );
-				return $module_settings;
-			},
-			array()
-		);
-	}
-
 	public function test_perflab_maybe_set_object_cache_dropin_no_conflict() {
 		global $wp_filesystem;
 
@@ -255,7 +173,7 @@ public function test_perflab_maybe_set_object_cache_dropin_no_conflict() {
 		// Run function to place drop-in and ensure it exists afterwards.
 		perflab_maybe_set_object_cache_dropin();
 		$this->assertTrue( $wp_filesystem->exists( WP_CONTENT_DIR . '/object-cache.php' ) );
-		$this->assertSame( file_get_contents( PERFLAB_PLUGIN_DIR_PATH . 'server-timing/object-cache.copy.php' ), $wp_filesystem->get_contents( WP_CONTENT_DIR . '/object-cache.php' ) );
+		$this->assertSame( file_get_contents( PERFLAB_PLUGIN_DIR_PATH . 'includes/server-timing/object-cache.copy.php' ), $wp_filesystem->get_contents( WP_CONTENT_DIR . '/object-cache.php' ) );
 	}
 
 	public function test_perflab_maybe_set_object_cache_dropin_no_conflict_but_failing() {
@@ -331,6 +249,6 @@ static function () {
 		WP_Filesystem();
 
 		// Simulate that the original object-cache.copy.php file exists.
-		$wp_filesystem->put_contents( PERFLAB_PLUGIN_DIR_PATH . 'server-timing/object-cache.copy.php', file_get_contents( PERFLAB_PLUGIN_DIR_PATH . 'server-timing/object-cache.copy.php' ) );
+		$wp_filesystem->put_contents( PERFLAB_PLUGIN_DIR_PATH . 'includes/server-timing/object-cache.copy.php', file_get_contents( PERFLAB_PLUGIN_DIR_PATH . 'includes/server-timing/object-cache.copy.php' ) );
 	}
 }