wp_cache_get
function prefix_get_post_count( $post_status = 'publish' ) {
$cache_key = 'prefix_post_count_'. $post_status;
$_posts = wp_cache_get( $cache_key );
if ( false === $_posts ) {
$_posts = $wpdb->get_var(
$wpdb->prepare(
"SELECT COUNT(*) FROM $wpdb->posts WHERE post_type = 'post' AND post_status = %s",
$post_status
));
wp_cache_set( $cache_key, $_posts );
}
return $_posts;
}