diff --git a/includes/cli-server/router.php b/includes/cli-server/router.php
index 2c3209d96..d7e85a3fe 100644
--- a/includes/cli-server/router.php
+++ b/includes/cli-server/router.php
@@ -9,28 +9,35 @@
 }
 
 $root = $_SERVER['DOCUMENT_ROOT'];
-$path = '/'. ltrim( parse_url( urldecode( $_SERVER['REQUEST_URI'] ),PHP_URL_PATH ), '/' );
+$path = '/' . ltrim(parse_url(urldecode($_SERVER['REQUEST_URI']), PHP_URL_PATH), '/');
 
 define('DB_ENGINE', getenv('DB_ENGINE') ?: 'mysql');
 
-if ( file_exists( $root.$path ) ) {
+// The self-call will slow down the response handling and will not benefit the test environment.
+global $wp_filter;
+$wp_filter['do_mu_upgrade'][10][] = [
+    'accepted_args' => 0,
+    'function' => static function () {
+        return false;
+    }
+];
 
-	// Enforces trailing slash, keeping links tidy in the admin
-	if ( is_dir( $root.$path ) && substr_compare($path, '/', -strlen('/')) !== 0 ) {
-		header( "Location: $path/" );
-		exit;
-	}
+if (file_exists($root . $path)) {
+    // Enforces trailing slash, keeping links tidy in the admin
+    if (is_dir($root . $path) && substr_compare($path, '/', -strlen('/')) !== 0) {
+        header("Location: $path/");
+        exit;
+    }
 
-	// Runs PHP file if it exists
-	if ( strpos($path, '.php') !== false ) {
-		chdir( dirname( $root.$path ) );
-		require_once $root.$path;
-	} else {
-		return false;
-	}
+    // Runs PHP file if it exists
+    if (strpos($path, '.php') !== false) {
+        chdir(dirname($root . $path));
+        require_once $root . $path;
+    } else {
+        return false;
+    }
 } else {
-
-	// Otherwise, run `index.php`
-	chdir( $root );
-	require_once 'index.php';
+    // Otherwise, run `index.php`
+    chdir($root);
+    require_once 'index.php';
 }
diff --git a/src/Module/WPLoader/Filters.php b/src/Module/WPLoader/Filters.php
deleted file mode 100644
index 336bd88a2..000000000
--- a/src/Module/WPLoader/Filters.php
+++ /dev/null
@@ -1,205 +0,0 @@
-<?php
-
-namespace lucatume\WPBrowser\Module\WPLoader;
-
-use Codeception\Exception\ModuleException;
-
-/**
- * Class Filters
- *
- * Handles operations on WordPress filters.
- *
- * @package lucatume\WPBrowser\Module\WPLoader
- */
-class Filters
-{
-
-    /**
-     * The default filter priority.
-     *
-     * @var int
-     */
-    protected $defaultPriority = 10;
-
-    /**
-     * The callable that should be used to remove the filter.
-     *
-     * @var callable
-     */
-    protected $removeWith;
-
-    /**
-     * The callable that should be used to add the filter.
-     *
-     * @var callable
-     */
-    protected $addWith;
-
-    /**
-     * The default number of accepted arguments.
-     *
-     * @var int
-     */
-    protected $defaultAcceptedArguments = 1;
-
-    /**
-     * The list of filters to remove.
-     *
-     * @var array<array<mixed>>
-     */
-    protected $toRemove = [];
-
-    /**
-     * The list of filters to add.
-     *
-     * @var array<array<mixed>>
-     */
-    protected $toAdd = [];
-
-    /**
-     * Filters constructor.
-     *
-     * @param array<array<mixed>> $filters The filters to manage.
-     */
-    public function __construct(array $filters = [])
-    {
-        $this->toRemove = !empty($filters['remove'])
-            ? array_map([$this, 'normalizeFilter'], $filters['remove'])
-            : [];
-        $this->toAdd = !empty($filters['add'])
-            ? array_map([$this, 'normalizeFilter'], $filters['add'])
-            : [];
-    }
-
-    /**
-     * Formats and normalizes a list of filters.
-     *
-     * @param array<array<mixed>> $filters The list of filters to format.
-     *
-     * @return array{remove: mixed[][], add: mixed[][]} The formatted list of filters.
-     */
-    public static function format(array $filters): array
-    {
-        $instance = new self($filters);
-
-        return $instance->toArray();
-    }
-
-    /**
-     * Returns the current state in array format.
-     *
-     * @return array{remove: mixed[][], add: mixed[][]} A map of the filters to remove and to add.j:w
-     */
-    public function toArray(): array
-    {
-        return [
-            'remove' => $this->toRemove,
-            'add' => $this->toAdd,
-        ];
-    }
-
-    /**
-     * Returns the list of filters to remove.
-     *
-     * @return FiltersGroup The group of filters to remove.
-     */
-    public function toRemove(): FiltersGroup
-    {
-        return new FiltersGroup($this->toRemove, $this->removeWith, $this->addWith);
-    }
-
-    /**
-     * Sets the callable that should be used to remove the filters.
-     *
-     * @param callable $removeWith The callable that should be used to remove the filters.
-     */
-    public function removeWith(callable $removeWith): void
-    {
-        $this->removeWith = $removeWith;
-    }
-
-    /**
-     * Sets the callable that should be used to remove the filters.
-     *
-     * @param callable $addWith The callable that should be used to add the filters.
-     */
-    public function addWith(callable $addWith): void
-    {
-        $this->addWith = $addWith;
-    }
-
-    /**
-     * Returns the list of filters to add.
-     *
-     * @return FiltersGroup The group of filters to add.
-     */
-    public function toAdd(): FiltersGroup
-    {
-        return new FiltersGroup($this->toAdd, $this->removeWith, $this->addWith);
-    }
-
-    /**
-     * Normalizes a filter contents.
-     *
-     * @param array<mixed> $filter The current filter state.
-     *
-     * @return array<mixed> The normalized filter.
-     *
-     * @throws ModuleException If the filters information is not complete or not coherent.
-     */
-    protected function normalizeFilter(array $filter): array
-    {
-        if (count($filter) < 2) {
-            throw new ModuleException(
-                __CLASS__,
-                'Callback ' . json_encode($filter) . ' does not specify enough data for a filter: '
-                . 'required at least tag and callback.'
-            );
-        }
-
-        if (empty($filter[0]) || !is_string($filter[0])) {
-            throw new ModuleException(__CLASS__, 'Callback ' . json_encode($filter) . ' does not specify a valid tag.');
-        }
-
-        if (count($filter) === 2) {
-            $filter[] = $this->defaultPriority;
-        }
-
-        if (count($filter) === 3) {
-            $filter[] = $this->defaultAcceptedArguments;
-        }
-
-        if (count($filter) > 4) {
-            throw new ModuleException(
-                __CLASS__,
-                'Callback ' . json_encode($filter) . ' contains too many arguments; '
-                .'only tag, callback, priority and accepted arguments are supported'
-            );
-        }
-
-
-        $callbackFunc = $filter[1];
-
-        if (empty($callbackFunc) || !(is_string($callbackFunc) || is_array($callbackFunc))) {
-            throw new ModuleException(
-                __CLASS__,
-                'Callback for ' . json_encode($filter) . ' is empty or the wrong type: '
-                .'it should be a string (a function name) or an array of two strings (class name and a static method).'
-            );
-        }
-
-        if (is_array($callbackFunc)) {
-            if (count($callbackFunc) !== 2
-                || count(array_filter($callbackFunc, 'is_string')) !== 2
-            ) {
-                throw new ModuleException(
-                    __CLASS__,
-                    'Callback for ' . json_encode($filter) . ' is weird: '
-                    .'it should be a string (function name) or an array of two strings (class name and static method).'
-                );
-            }
-        }
-
-        return $filter;
-    }
-}
diff --git a/src/Module/WPLoader/FiltersGroup.php b/src/Module/WPLoader/FiltersGroup.php
deleted file mode 100644
index 3e7628a5f..000000000
--- a/src/Module/WPLoader/FiltersGroup.php
+++ /dev/null
@@ -1,76 +0,0 @@
-<?php
-/**
- * Models a group of WordPress filters to be added or removed together.
- *
- * @package lucatume\WPBrowser\Module\WPLoader
- */
-
-namespace lucatume\WPBrowser\Module\WPLoader;
-
-/**
- * Class FiltersGroup
- *
- * @package lucatume\WPBrowser\Module\WPLoader
- */
-class FiltersGroup
-{
-    /**
-     * @var array<array<mixed>>
-     */
-    protected $filters = [];
-    /**
-     * The callback that will be used to remove filters.
-     *
-     * @var callable
-     */
-    protected $removeCallback;
-
-    /**
-     * The callback that will be used to add filters.
-     *
-     * @var callable
-     */
-    protected $addCallback;
-
-    /**
-     * FiltersGroup constructor.
-     *
-     * @param array<array<mixed>> $filters    The list of filters to manage.
-     * @param callable|null $removeWith       The callable that should be used to remove the filters or `null` to use
-     *                                        the default one.
-     * @param callable|null       $addWith    The callable that should be used to add the filters, or `null` to use the
-     */
-    public function __construct(
-        array $filters = [],
-        callable $removeWith = null,
-        callable $addWith = null
-    ) {
-        /**
-         * An array detailing each filter callback, priority and arguments.
-         */
-        $this->filters = $filters;
-        $this->removeCallback = $removeWith ?? 'remove_filter';
-        $this->addCallback    = $addWith ?? 'add_filter';
-    }
-
-    /**
-     * Removes the filters of the group.
-     */
-    public function remove(): void
-    {
-        foreach ($this->filters as $filter) {
-            $filterWithoutAcceptedArguments = array_slice($filter, 0, 3);
-            call_user_func_array($this->removeCallback, $filterWithoutAcceptedArguments);
-        }
-    }
-
-    /**
-     * Adds the filters of the group.
-     */
-    public function add(): void
-    {
-        foreach ($this->filters as $filter) {
-            call_user_func_array($this->addCallback, $filter);
-        }
-    }
-}
diff --git a/tests/unit/lucatume/WPBrowser/Events/Module/WPLoader/FiltersTest.php b/tests/unit/lucatume/WPBrowser/Events/Module/WPLoader/FiltersTest.php
deleted file mode 100644
index 06fc0170d..000000000
--- a/tests/unit/lucatume/WPBrowser/Events/Module/WPLoader/FiltersTest.php
+++ /dev/null
@@ -1,200 +0,0 @@
-<?php
-
-namespace lucatume\WPBrowser\Module\WPLoader;
-
-use Codeception\Exception\ModuleException;
-use Codeception\Test\Unit;
-use stdClass;
-
-class FiltersTest extends Unit
-{
-    /**
-     * It should allow setting filters to remove
-     *
-     * @test
-     */
-    public function should_allow_setting_filters_to_remove()
-    {
-        $sut = new Filters([
-            'remove' => [
-                [ 'some-filter', 'some_callback', 23 ],
-                [ 'some-other-filter', 'some_callback' ],
-                [ 'some-filter', 'some_callback' ],
-            ]
-        ]);
-
-        $removed = [];
-        $sut->removeWith(function ($tag, $callback, $priority) use (&$removed) {
-            $removed[] = [ $tag, $callback, $priority ];
-
-            return true;
-        });
-
-        $sut->toRemove()->remove();
-
-        $this->assertEquals([
-            [ 'some-filter', 'some_callback', 23 ],
-            [ 'some-other-filter', 'some_callback', 10 ],
-            [ 'some-filter', 'some_callback', 10 ],
-        ], $removed);
-    }
-
-    /**
-     * It should allow readding removed filters
-     *
-     * @test
-     */
-    public function should_allow_readding_removed_filters()
-    {
-        $sut = new Filters([
-            'remove' => [
-                [ 'some-filter', 'some_callback', 23 ],
-                [ 'some-other-filter', 'some_callback', 10, 2 ],
-                [ 'some-filter', 'some_callback' ],
-            ]
-        ]);
-
-        $added = [];
-        $sut->removeWith(function ($tag, $callback, $priority) {
-        });
-        $sut->addWith(function ($tag, $callback, $priority, $acceptedArgs) use (&$added) {
-            $added[] = [ $tag, $callback, $priority, $acceptedArgs ];
-        });
-
-        $sut->toRemove()->add();
-
-        $this->assertEquals([
-            [ 'some-filter', 'some_callback', 23, 1 ],
-            [ 'some-other-filter', 'some_callback', 10, 2 ],
-            [ 'some-filter', 'some_callback', 10, 1 ],
-        ], $added);
-    }
-
-    /**
-     * It should allow setting filters to add
-     *
-     * @test
-     */
-    public function should_allow_setting_filters_to_add()
-    {
-        $sut = new Filters([
-            'add' => [
-                [ 'some-filter', 'some_callback', 23 ],
-                [ 'some-other-filter', 'some_callback' ],
-                [ 'some-filter', 'some_callback', 12, 3 ],
-            ]
-        ]);
-
-        $added = [];
-        $sut->addWith(function ($tag, $callback, $priority, $acceptedArgs) use (&$added) {
-            $added[] = [ $tag, $callback, $priority, $acceptedArgs ];
-
-            return true;
-        });
-
-        $sut->toAdd()->add();
-
-        $this->assertEquals([
-            [ 'some-filter', 'some_callback', 23, 1 ],
-            [ 'some-other-filter', 'some_callback', 10, 1 ],
-            [ 'some-filter', 'some_callback', 12, 3 ],
-        ], $added);
-    }
-
-    /**
-     * It should allow removing added filters
-     *
-     * @test
-     */
-    public function should_allow_removing_added_filters()
-    {
-        $sut = new Filters([
-            'add' => [
-                [ 'some-filter', 'some_callback', 23 ],
-                [ 'some-other-filter', 'some_callback' ],
-                [ 'some-filter', 'some_callback', 12, 3 ],
-            ]
-        ]);
-
-        $removed = [];
-        $sut->addWith(function () {
-        });
-        $sut->removeWith(function ($tag, $callback, $priority) use (&$removed) {
-            $removed[] = [ $tag, $callback, $priority ];
-        });
-
-        $sut->toAdd()->remove();
-
-        $this->assertEquals([
-            [ 'some-filter', 'some_callback', 23 ],
-            [ 'some-other-filter', 'some_callback', 10 ],
-            [ 'some-filter', 'some_callback', 12 ],
-        ], $removed);
-    }
-
-    /**
-     * It should allow formatting the filters
-     *
-     * @test
-     */
-    public function should_allow_formatting_the_filters()
-    {
-        $formatted = Filters::format([
-            'foo'    => 'bar',
-            'add'    => [
-                [ 'one', 'foo', 11 ],
-                [ 'one', 'bar' ],
-                [ 'two', 'foo', 23, 2 ],
-            ],
-            'remove' => [
-                [ 'one', 'foo', 11 ],
-                [ 'one', 'bar' ],
-                [ 'two', 'foo', 23, 2 ],
-            ]
-        ]);
-
-        $this->assertEquals([
-            'remove' => [
-                [ 'one', 'foo', 11, 1 ],
-                [ 'one', 'bar', 10, 1 ],
-                [ 'two', 'foo', 23, 2 ],
-            ],
-            'add'    => [
-                [ 'one', 'foo', 11, 1 ],
-                [ 'one', 'bar', 10, 1 ],
-                [ 'two', 'foo', 23, 2 ],
-            ]
-        ], $formatted);
-    }
-
-    public function badFilters(): array
-    {
-        return [
-            [ [ 'foo', new stdClass() ] ],
-            [ [ new stdClass(), 'foo' ] ],
-            [ [ '', new stdClass() ] ],
-            [ [ '', '' ] ],
-            [ [ '' ] ],
-            [ [] ],
-            [ [ 'foo', [ 'bar' ] ] ],
-            [ [ 'foo', [ 'bar', new stdClass() ] ] ],
-            [ [ 'foo', [ new stdClass(), 'bar' ] ] ],
-            [ [ 'foo', 'bar', 10, 12, 23 ] ],
-        ];
-    }
-
-    /**
-     * It should throw if filters information is not correct
-     *
-     * @test
-     *
-     * @dataProvider badFilters
-     */
-    public function should_throw_if_filters_information_is_not_correct(array $filters)
-    {
-        $this->expectException(ModuleException::class);
-        new Filters([
-            'remove' => [ $filters ]
-        ]);
-    }
-}