Really old post, sorry @kulturbanause, didn’t see you’re follow up back then. To clarify my previous comment, I don’t actually use the value returned from
$meta = get_post_meta($post_id);
instead I just use that function call for force WP to get every custom field for a post. Once that is done then I use get_field() and other ACF functions because the values are cached and the WP cache. It is just a way to reduce DB requests.
@kcalv, you could also use a persistent cache that can cache html fragments for this, or even the WP the WP Transients API https://codex.wordpress.org/Transients_API
