[@robin-w Moderator 5 years, 1 month ago]

this is the code bbpress uses

$topics_query = array(

					// What and how
					'post_type'      => bbp_get_topic_post_type(),
					'post_status'    => bbp_get_public_topic_statuses(),
					'post_parent'    => $settings['parent_forum'],
					'posts_per_page' => (int) $settings['max_shown'],
					'meta_query'     => array( array(
						'key'  => '_bbp_reply_count',
						'type' => 'NUMERIC'
					) ),

					// Ordering
					'orderby' => 'meta_value_num',
					'order'   => 'DESC',

					// Performance
					'ignore_sticky_posts'    => true,
					'no_found_rows'          => true,
					'update_post_term_cache' => false,
					'update_post_meta_cache' => false
				);