diff --git a/system/Autoloader/FileLocator.php b/system/Autoloader/FileLocator.php
index 6f241e847be3..8a6640d986d0 100644
--- a/system/Autoloader/FileLocator.php
+++ b/system/Autoloader/FileLocator.php
@@ -17,7 +17,7 @@
  *
  * @see \CodeIgniter\Autoloader\FileLocatorTest
  */
-class FileLocator
+class FileLocator implements FileLocatorInterface
 {
     /**
      * The Autoloader to use.
diff --git a/system/Autoloader/FileLocatorCached.php b/system/Autoloader/FileLocatorCached.php
new file mode 100644
index 000000000000..8bc8d1e85ee9
--- /dev/null
+++ b/system/Autoloader/FileLocatorCached.php
@@ -0,0 +1,172 @@
+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Autoloader;
+
+use CodeIgniter\Cache\CacheInterface;
+use CodeIgniter\Cache\FactoriesCache\FileVarExportHandler;
+
+/**
+ * FileLocator with Cache
+ *
+ * @see \CodeIgniter\Autoloader\FileLocatorCachedTest
+ */
+final class FileLocatorCached implements FileLocatorInterface
+{
+    private FileLocator $locator;
+
+    /**
+     * @var CacheInterface|FileVarExportHandler
+     */
+    private $cacheHandler;
+
+    /**
+     * Cache data
+     *
+     * [method => data]
+     * E.g.,
+     * [
+     *     'search' => [$path => $foundPaths],
+     * ]
+     */
+    private array $cache = [];
+
+    /**
+     * Is the cache updated?
+     */
+    private bool $cacheUpdated = false;
+
+    private string $cacheKey = 'FileLocatorCache';
+
+    /**
+     * @param CacheInterface|FileVarExportHandler|null $cache
+     */
+    public function __construct(FileLocator $locator, $cache = null)
+    {
+        $this->cacheHandler = $cache ?? new FileVarExportHandler();
+        $this->locator      = $locator;
+
+        $this->loadCache();
+    }
+
+    private function loadCache(): void
+    {
+        $data = $this->cacheHandler->get($this->cacheKey);
+
+        if (is_array($data)) {
+            $this->cache = $data;
+        }
+    }
+
+    public function __destruct()
+    {
+        $this->saveCache();
+    }
+
+    private function saveCache(): void
+    {
+        if ($this->cacheUpdated) {
+            $this->cacheHandler->save($this->cacheKey, $this->cache, 3600 * 24);
+        }
+    }
+
+    /**
+     * Delete cache data
+     */
+    public function deleteCache(): void
+    {
+        $this->cacheHandler->delete($this->cacheKey);
+    }
+
+    public function findQualifiedNameFromPath(string $path): false|string
+    {
+        if (isset($this->cache['findQualifiedNameFromPath'][$path])) {
+            return $this->cache['findQualifiedNameFromPath'][$path];
+        }
+
+        $classname = $this->locator->findQualifiedNameFromPath($path);
+
+        $this->cache['findQualifiedNameFromPath'][$path] = $classname;
+        $this->cacheUpdated                              = true;
+
+        return $classname;
+    }
+
+    public function getClassname(string $file): string
+    {
+        if (isset($this->cache['getClassname'][$file])) {
+            return $this->cache['getClassname'][$file];
+        }
+
+        $classname = $this->locator->getClassname($file);
+
+        $this->cache['getClassname'][$file] = $classname;
+        $this->cacheUpdated                 = true;
+
+        return $classname;
+    }
+
+    public function search(string $path, string $ext = 'php', bool $prioritizeApp = true): array
+    {
+        if (isset($this->cache['search'][$path][$ext][$prioritizeApp])) {
+            return $this->cache['search'][$path][$ext][$prioritizeApp];
+        }
+
+        $foundPaths = $this->locator->search($path, $ext, $prioritizeApp);
+
+        $this->cache['search'][$path][$ext][$prioritizeApp] = $foundPaths;
+        $this->cacheUpdated                                 = true;
+
+        return $foundPaths;
+    }
+
+    public function listFiles(string $path): array
+    {
+        if (isset($this->cache['listFiles'][$path])) {
+            return $this->cache['listFiles'][$path];
+        }
+
+        $files = $this->locator->listFiles($path);
+
+        $this->cache['listFiles'][$path] = $files;
+        $this->cacheUpdated              = true;
+
+        return $files;
+    }
+
+    public function listNamespaceFiles(string $prefix, string $path): array
+    {
+        if (isset($this->cache['listNamespaceFiles'][$prefix][$path])) {
+            return $this->cache['listNamespaceFiles'][$prefix][$path];
+        }
+
+        $files = $this->locator->listNamespaceFiles($prefix, $path);
+
+        $this->cache['listNamespaceFiles'][$prefix][$path] = $files;
+        $this->cacheUpdated                                = true;
+
+        return $files;
+    }
+
+    public function locateFile(string $file, ?string $folder = null, string $ext = 'php'): false|string
+    {
+        if (isset($this->cache['locateFile'][$file][$folder][$ext])) {
+            return $this->cache['locateFile'][$file][$folder][$ext];
+        }
+
+        $files = $this->locator->locateFile($file, $folder, $ext);
+
+        $this->cache['locateFile'][$file][$folder][$ext] = $files;
+        $this->cacheUpdated                              = true;
+
+        return $files;
+    }
+}
diff --git a/system/Autoloader/FileLocatorInterface.php b/system/Autoloader/FileLocatorInterface.php
new file mode 100644
index 000000000000..8f7b551bb02f
--- /dev/null
+++ b/system/Autoloader/FileLocatorInterface.php
@@ -0,0 +1,80 @@
+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Autoloader;
+
+/**
+ * Allows loading non-class files in a namespaced manner.
+ * Works with Helpers, Views, etc.
+ */
+interface FileLocatorInterface
+{
+    /**
+     * Attempts to locate a file by examining the name for a namespace
+     * and looking through the PSR-4 namespaced files that we know about.
+     *
+     * @param string      $file   The relative file path or namespaced file to
+     *                            locate. If not namespaced, search in the app
+     *                            folder.
+     * @param string|null $folder The folder within the namespace that we should
+     *                            look for the file. If $file does not contain
+     *                            this value, it will be appended to the namespace
+     *                            folder.
+     * @param string      $ext    The file extension the file should have.
+     *
+     * @return false|string The path to the file, or false if not found.
+     */
+    public function locateFile(string $file, ?string $folder = null, string $ext = 'php');
+
+    /**
+     * Examines a file and returns the fully qualified class name.
+     */
+    public function getClassname(string $file): string;
+
+    /**
+     * Searches through all of the defined namespaces looking for a file.
+     * Returns an array of all found locations for the defined file.
+     *
+     * Example:
+     *
+     *  $locator->search('Config/Routes.php');
+     *  // Assuming PSR4 namespaces include foo and bar, might return:
+     *  [
+     *      'app/Modules/foo/Config/Routes.php',
+     *      'app/Modules/bar/Config/Routes.php',
+     *  ]
+     */
+    public function search(string $path, string $ext = 'php', bool $prioritizeApp = true): array;
+
+    /**
+     * Find the qualified name of a file according to
+     * the namespace of the first matched namespace path.
+     *
+     * @return false|string The qualified name or false if the path is not found
+     */
+    public function findQualifiedNameFromPath(string $path);
+
+    /**
+     * Scans the defined namespaces, returning a list of all files
+     * that are contained within the subpath specified by $path.
+     *
+     * @return string[] List of file paths
+     */
+    public function listFiles(string $path): array;
+
+    /**
+     * Scans the provided namespace, returning a list of all files
+     * that are contained within the sub path specified by $path.
+     *
+     * @return string[] List of file paths
+     */
+    public function listNamespaceFiles(string $prefix, string $path): array;
+}
diff --git a/system/CLI/Commands.php b/system/CLI/Commands.php
index df28e533a354..bc4d1befc6fb 100644
--- a/system/CLI/Commands.php
+++ b/system/CLI/Commands.php
@@ -11,7 +11,7 @@
 
 namespace CodeIgniter\CLI;
 
-use CodeIgniter\Autoloader\FileLocator;
+use CodeIgniter\Autoloader\FileLocatorInterface;
 use CodeIgniter\Log\Logger;
 use ReflectionClass;
 use ReflectionException;
@@ -87,7 +87,7 @@ public function discoverCommands()
             return;
         }
 
-        /** @var FileLocator $locator */
+        /** @var FileLocatorInterface $locator */
         $locator = service('locator');
         $files   = $locator->listFiles('Commands/');
 
diff --git a/system/Commands/Utilities/Routes/ControllerFinder.php b/system/Commands/Utilities/Routes/ControllerFinder.php
index f801d531fa92..1528996968f1 100644
--- a/system/Commands/Utilities/Routes/ControllerFinder.php
+++ b/system/Commands/Utilities/Routes/ControllerFinder.php
@@ -11,7 +11,7 @@
 
 namespace CodeIgniter\Commands\Utilities\Routes;
 
-use CodeIgniter\Autoloader\FileLocator;
+use CodeIgniter\Autoloader\FileLocatorInterface;
 use CodeIgniter\Config\Services;
 
 /**
@@ -26,7 +26,7 @@ final class ControllerFinder
      */
     private string $namespace;
 
-    private FileLocator $locator;
+    private FileLocatorInterface $locator;
 
     /**
      * @param string $namespace namespace to search
diff --git a/system/Config/BaseService.php b/system/Config/BaseService.php
index b66b8c9f535e..0a5df0ffec4c 100644
--- a/system/Config/BaseService.php
+++ b/system/Config/BaseService.php
@@ -13,6 +13,7 @@
 
 use CodeIgniter\Autoloader\Autoloader;
 use CodeIgniter\Autoloader\FileLocator;
+use CodeIgniter\Autoloader\FileLocatorInterface;
 use CodeIgniter\Cache\CacheInterface;
 use CodeIgniter\Cache\ResponseCache;
 use CodeIgniter\CLI\Commands;
@@ -226,7 +227,7 @@ public static function autoloader(bool $getShared = true)
      * within namespaced folders, as well as convenience methods for
      * loading 'helpers', and 'libraries'.
      *
-     * @return FileLocator
+     * @return FileLocatorInterface
      */
     public static function locator(bool $getShared = true)
     {
diff --git a/system/Publisher/Publisher.php b/system/Publisher/Publisher.php
index e40a14c88905..ca9b4eb09a79 100644
--- a/system/Publisher/Publisher.php
+++ b/system/Publisher/Publisher.php
@@ -11,7 +11,7 @@
 
 namespace CodeIgniter\Publisher;
 
-use CodeIgniter\Autoloader\FileLocator;
+use CodeIgniter\Autoloader\FileLocatorInterface;
 use CodeIgniter\Files\FileCollection;
 use CodeIgniter\HTTP\URI;
 use CodeIgniter\Publisher\Exceptions\PublisherException;
@@ -105,7 +105,7 @@ final public static function discover(string $directory = 'Publishers'): array
 
         self::$discovered[$directory] = [];
 
-        /** @var FileLocator $locator */
+        /** @var FileLocatorInterface $locator */
         $locator = service('locator');
 
         if ([] === $files = $locator->listFiles($directory)) {
diff --git a/system/Router/RouteCollection.php b/system/Router/RouteCollection.php
index ca080152ff28..d38faa41278d 100644
--- a/system/Router/RouteCollection.php
+++ b/system/Router/RouteCollection.php
@@ -12,7 +12,7 @@
 namespace CodeIgniter\Router;
 
 use Closure;
-use CodeIgniter\Autoloader\FileLocator;
+use CodeIgniter\Autoloader\FileLocatorInterface;
 use CodeIgniter\Router\Exceptions\RouterException;
 use Config\App;
 use Config\Modules;
@@ -245,7 +245,7 @@ class RouteCollection implements RouteCollectionInterface
     /**
      * Handle to the file locator to use.
      *
-     * @var FileLocator
+     * @var FileLocatorInterface
      */
     protected $fileLocator;
 
@@ -283,7 +283,7 @@ class RouteCollection implements RouteCollectionInterface
     /**
      * Constructor
      */
-    public function __construct(FileLocator $locator, Modules $moduleConfig, Routing $routing)
+    public function __construct(FileLocatorInterface $locator, Modules $moduleConfig, Routing $routing)
     {
         $this->fileLocator  = $locator;
         $this->moduleConfig = $moduleConfig;
diff --git a/system/View/Parser.php b/system/View/Parser.php
index 120570079d2b..a948579e8f8f 100644
--- a/system/View/Parser.php
+++ b/system/View/Parser.php
@@ -11,7 +11,7 @@
 
 namespace CodeIgniter\View;
 
-use CodeIgniter\Autoloader\FileLocator;
+use CodeIgniter\Autoloader\FileLocatorInterface;
 use CodeIgniter\View\Exceptions\ViewException;
 use Config\View as ViewConfig;
 use ParseError;
@@ -79,10 +79,15 @@ class Parser extends View
     /**
      * Constructor
      *
-     * @param FileLocator|null $loader
+     * @param FileLocatorInterface|null $loader
      */
-    public function __construct(ViewConfig $config, ?string $viewPath = null, $loader = null, ?bool $debug = null, ?LoggerInterface $logger = null)
-    {
+    public function __construct(
+        ViewConfig $config,
+        ?string $viewPath = null,
+        $loader = null,
+        ?bool $debug = null,
+        ?LoggerInterface $logger = null
+    ) {
         // Ensure user plugins override core plugins.
         $this->plugins = $config->plugins;
 
diff --git a/system/View/View.php b/system/View/View.php
index e8fdf5f18f7e..ffb734779de1 100644
--- a/system/View/View.php
+++ b/system/View/View.php
@@ -11,7 +11,7 @@
 
 namespace CodeIgniter\View;
 
-use CodeIgniter\Autoloader\FileLocator;
+use CodeIgniter\Autoloader\FileLocatorInterface;
 use CodeIgniter\Debug\Toolbar\Collectors\Views;
 use CodeIgniter\Filters\DebugToolbar;
 use CodeIgniter\View\Exceptions\ViewException;
@@ -63,7 +63,7 @@ class View implements RendererInterface
      * we need to attempt to find a view
      * that's not in standard place.
      *
-     * @var FileLocator
+     * @var FileLocatorInterface
      */
     protected $loader;
 
@@ -141,8 +141,13 @@ class View implements RendererInterface
      */
     protected $sectionStack = [];
 
-    public function __construct(ViewConfig $config, ?string $viewPath = null, ?FileLocator $loader = null, ?bool $debug = null, ?LoggerInterface $logger = null)
-    {
+    public function __construct(
+        ViewConfig $config,
+        ?string $viewPath = null,
+        ?FileLocatorInterface $loader = null,
+        ?bool $debug = null,
+        ?LoggerInterface $logger = null
+    ) {
         $this->config   = $config;
         $this->viewPath = rtrim($viewPath, '\\/ ') . DIRECTORY_SEPARATOR;
         $this->loader   = $loader ?? Services::locator();
diff --git a/tests/system/Autoloader/FileLocatorCachedTest.php b/tests/system/Autoloader/FileLocatorCachedTest.php
new file mode 100644
index 000000000000..f3871713d171
--- /dev/null
+++ b/tests/system/Autoloader/FileLocatorCachedTest.php
@@ -0,0 +1,83 @@
+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Autoloader;
+
+use CodeIgniter\Cache\FactoriesCache\FileVarExportHandler;
+use Config\Autoload;
+use Config\Modules;
+
+/**
+ * @internal
+ *
+ * @group Others
+ */
+final class FileLocatorCachedTest extends FileLocatorTest
+{
+    private FileVarExportHandler $handler;
+    protected FileLocatorInterface $locator;
+
+    public static function tearDownAfterClass(): void
+    {
+        parent::tearDownAfterClass();
+
+        // Delete cache file.
+        $autoloader  = new Autoloader();
+        $handler     = new FileVarExportHandler();
+        $fileLocator = new FileLocator($autoloader);
+        $locator     = new FileLocatorCached($fileLocator, $handler);
+        $locator->deleteCache();
+    }
+
+    protected function setUp(): void
+    {
+        parent::setUp();
+
+        $autoloader = new Autoloader();
+        $autoloader->initialize(new Autoload(), new Modules());
+        $autoloader->addNamespace([
+            'Unknown'       => '/i/do/not/exist',
+            'Tests/Support' => TESTPATH . '_support/',
+            'App'           => APPPATH,
+            'CodeIgniter'   => [
+                TESTPATH,
+                SYSTEMPATH,
+            ],
+            'Errors'              => APPPATH . 'Views/errors',
+            'System'              => SUPPORTPATH . 'Autoloader/system',
+            'CodeIgniter\\Devkit' => [
+                TESTPATH . '_support/',
+            ],
+            'Acme\SampleProject' => TESTPATH . '_support',
+            'Acme\Sample'        => TESTPATH . '_support/does/not/exists',
+        ]);
+
+        $this->handler = new FileVarExportHandler();
+        $fileLocator   = new FileLocator($autoloader);
+        $this->locator = new FileLocatorCached($fileLocator, $this->handler);
+    }
+
+    protected function tearDown(): void
+    {
+        $this->locator->__destruct();
+
+        parent::tearDown();
+    }
+
+    public function testDeleteCache()
+    {
+        $this->assertNotSame([], $this->handler->get('FileLocatorCache'));
+
+        $this->locator->deleteCache();
+
+        $this->assertFalse($this->handler->get('FileLocatorCache'));
+    }
+}
diff --git a/tests/system/Autoloader/FileLocatorTest.php b/tests/system/Autoloader/FileLocatorTest.php
index 0d084280f520..14c512493d26 100644
--- a/tests/system/Autoloader/FileLocatorTest.php
+++ b/tests/system/Autoloader/FileLocatorTest.php
@@ -20,10 +20,11 @@
  * @internal
  *
  * @group Others
+ * @no-final
  */
-final class FileLocatorTest extends CIUnitTestCase
+class FileLocatorTest extends CIUnitTestCase
 {
-    private FileLocator $locator;
+    protected FileLocatorInterface $locator;
 
     protected function setUp(): void
     {
diff --git a/user_guide_src/source/changelogs/v4.5.0.rst b/user_guide_src/source/changelogs/v4.5.0.rst
index 89910fa84f3d..f7728e7cf9e1 100644
--- a/user_guide_src/source/changelogs/v4.5.0.rst
+++ b/user_guide_src/source/changelogs/v4.5.0.rst
@@ -51,6 +51,14 @@ Interface Changes
 Method Signature Changes
 ========================
 
+FileLocatorInterface
+--------------------
+
+- **Router:** The first parameter of the ``RouteCollection`` constructor has been changed
+  from ``FileLocator`` to ``FileLocatorInterface``.
+- **View:** The third parameter of the ``View`` constructor has been changed
+  from ``FileLocator`` to ``FileLocatorInterface``.
+
 Return Type Changes
 -------------------
 
@@ -123,9 +131,12 @@ Helpers and Functions
 Others
 ======
 
-- **Autoloader:** Autoloading performance when using Composer has been improved.
-  Adding the ``App`` namespace in the ``autoload.psr4`` setting in **composer.json**
-  may also improve the performance of your app. See :ref:`autoloader-application-namespace`.
+- **Autoloader:**
+    - Autoloading performance when using Composer has been improved.
+      Adding the ``App`` namespace in the ``autoload.psr4`` setting in **composer.json**
+      may also improve the performance of your app. See :ref:`autoloader-application-namespace`.
+    - FileLocator Caching implemented. See :ref:`file-locator-caching` for details.
+    - ``FileLocatorInterface`` has been added.
 - **CodeIgniter:** Added a pseudo-variable ``{memory_usage}`` to show your memory
   usage in your view files, which was supported by CodeIgniter 3.
 
diff --git a/user_guide_src/source/concepts/autoloader.rst b/user_guide_src/source/concepts/autoloader.rst
index cc47162e5c0c..62aa0f157cf3 100644
--- a/user_guide_src/source/concepts/autoloader.rst
+++ b/user_guide_src/source/concepts/autoloader.rst
@@ -140,3 +140,51 @@ autoloader will be the first one to get a chance to locate the file.
 
 .. note:: Prior to v4.5.0, if the same namespace was defined in both CodeIgniter and Composer, CodeIgniter's autoloader was
     the first one to get a chance to locate the file.
+
+.. _file-locator-caching:
+
+*******************
+FileLocator Caching
+*******************
+
+.. versionadded:: 4.5.0
+
+**FileLocator** is responsible for finding files or getting a classname from a file,
+which cannot be achieved with PHP autoloading.
+
+To improve its performance, FileLocator Caching has been implemented.
+
+How It Works
+============
+
+- Save the all found data by FileLocator into a cache file when destructing,
+  if the cache data is updated.
+- Restore cached data when instantiating if cached data is available.
+
+The cached data are used permanently.
+
+How to Delete Cached Data
+=========================
+
+Once stored, the cached data never expire.
+
+So if you add or remove files or change existing file paths, or namespaces, old
+cached data will be returned and your app may not work properly.
+
+In that case, you must manually delete the cache file. If you add a CodeIgniter
+package via Composer, you also need to delete the cache file.
+
+You can use the ``spark cache:clear`` command:
+
+.. code-block:: console
+
+    php spark cache:clear
+
+Or simply delete the **writable/cache/FileLocatorCache** file.
+
+How to Enable FileLocator Caching
+=================================
+
+Add the following code in **app/Config/Services.php**:
+
+.. literalinclude:: autoloader/004.php
diff --git a/user_guide_src/source/concepts/autoloader/004.php b/user_guide_src/source/concepts/autoloader/004.php
new file mode 100644
index 000000000000..090149e6486c
--- /dev/null
+++ b/user_guide_src/source/concepts/autoloader/004.php
@@ -0,0 +1,25 @@
+<?php
+
+namespace Config;
+
+use CodeIgniter\Autoloader\FileLocator;
+use CodeIgniter\Autoloader\FileLocatorCached;
+use CodeIgniter\Config\BaseService;
+
+class Services extends BaseService
+{
+    // ...
+
+    public static function locator(bool $getShared = true)
+    {
+        if ($getShared) {
+            if (! isset(static::$instances['locator'])) {
+                static::$instances['locator'] = new FileLocatorCached(new FileLocator(static::autoloader()));
+            }
+
+            return static::$mocks['locator'] ?? static::$instances['locator'];
+        }
+
+        return new FileLocator(static::autoloader());
+    }
+}