PerformanceController.php

<?php

namespace Drupal\system\Controller;

use Drupal\Core\Controller\ControllerBase;
use Drupal\system\Form\ClearCacheForm;
use Drupal\system\Form\PerformanceForm;

/**
 * Controller for performance admin.
 */
class PerformanceController extends ControllerBase {
    
    /**
     * Displays the system performance page.
     *
     * @return array
     *   A render array containing the cache-clear form and performance
     *   configuration form.
     */
    public function build() : array {
        // Load the cache form and embed it in a details element.
        $cache_clear = $this->formBuilder()
            ->getForm(ClearCacheForm::class);
        $cache_clear['clear_cache'] = [
            '#type' => 'details',
            '#title' => $this->t('Clear cache'),
            '#open' => TRUE,
            'clear' => $cache_clear['clear'],
        ];
        unset($cache_clear['clear']);
        return [
            'cache_clear' => $cache_clear,
            'performance' => $this->formBuilder()
                ->getForm(PerformanceForm::class),
        ];
    }

}