Thread:Manual talk:Extension registration/Caching only via APC?

The page informs that you need to use APC or APCu for caching (supposedly for PHP <= 5.4) to improve loading of many extensions.
 * 1) What about other caching mechanisms such as e.g. memcached or redis?
 * 2) What about PHP >= 5.5? Will the natively provided caching be enough for this job?