How to optimize Method Visibility and code structures for better performance?
Everything looks good enough.

Code style is OK.

You are using curl, so it will be quite fast and there is nothing you can do in the code to speed it up.

You may or may not need to check this:

    if($id){   // (1)
        $url = 'website/api/v1/pro/'.$id; // (2)
    }


depends from where this $id comes, you probably need to sanitize it somehow. see (1)

In same place you overwrite the $url. see (2) You probably want this:

    if($id){   
        $url = $url . 'website/api/v1/pro/'.$id;
    }


I also do not see where you do curl_close($ch) in case an error happen.