WP_Optimize::loader causing massive performance issues

The WP_Optimize::loader does not properly check the $class_name, leading to significant performance issues and even 504 Gateway Time-outs.

This problem occurs when other plugins or themes also use an autoloader registered with spl_autoload_register. The issue is exacerbated in your case because you do not use namespaces or follow the PSR-4 standard (https://www.php-fig.org/psr/psr-4/).

A quick fix is to validate the $class_name type like this:

private function loader($class_name) {
if ($class_name === 'int' || $class_name === 'string' || $class_name === 'bool') {
return;
}
$dirs = $this->get_class_directories();
// ...
}

However, a more robust solution would be to implement namespaces and adhere to PSR-4 standards.