More performant:

```php
$success = false;

if ($this->cache) {
    $this->acl = $this->cache->getItem($this->cacheKey, $success = null);
}

if (! $success || ! $this->acl) {
    $this->loadAcl();

    if ($this->cache) {
        $this->cache->setItem(self::CACHE_NAME, $this->acl);
    } 
}
```