Better way to get tag stats?

I addressed a similar problem not long ago – it’s all in the memory:

$post_ids = get_posts(
    array(
        'posts_per_page' => -1,
        'post_status'  => 'publish',
        'fields' => 'ids', // Just grab IDs instead of pulling 1000's of objects into memory
    )
);

update_object_term_cache( $post_ids, 'post' ); // Cache all the post terms in one query, memory should be ok

foreach ( $post_ids as $post_id ) {
    if ( ! $tags = get_object_term_cache( $post_id, 'post_tag' ) ) {
       $zerotags++;
    } else {
        $tag_count = count( $tags );

        if ( $tag_count === 1 ) {
            $onetag++;
        } elseif ( $tag_count === 2 ) {
            $twotags++;
        } elseif ( $tag_count >= 6 ) {
            $sixtags_plus++;
        }

        if ( $tag_count > 2 && $tag_count < 6 ) {
            $morethantwo++;
        }
    }
}

Update: Switched get_the_tags to get_object_term_cache – otherwise we lose all our hard work! (the former hits get_post, which will hit the db on every iteration and chuck the post object into memory – props @Pieter Goosen).

Update 2: The second argument for update_object_term_cache should be the post type, not the taxonomy.