output buffering is slow

Looking at the code, it seems that you are unnecessarily slowing things down by using output buffering.

if( $shauns_wp_query->have_posts() ) {
		$output = do_shortcode( $content );
		ob_start();
		echo $output;
		$output = ob_get_contents();;
		ob_end_clean();
	}

should be

if( $shauns_wp_query->have_posts() ) {
		$output = do_shortcode( $content );
	}

http://ww.wp.xz.cn/plugins/shauns-wp-query-shortcode/