Minimize WordPress default query.

gistfile1.aw

function alter_the_query( $request ) {
	$dummy_query = new WP_Query();  // the query isn't run if we don't pass any query vars
	$dummy_query->parse_query( $request );

	// @TODO sometimes this will help reduce queries, but sometimes won't
	$args = array(
		'showposts' => 1,
		'update_post_term_cache' => 0,
		'update_post_meta_cache' => 0,
		'no_found_rows' => 1 // if showposts = -1, useless
	);

	// this is the actual manipulation; do whatever you need here	
	if ( $dummy_query->is_home() ) {
		$request = array_merge( $args, array(
			'post_type' => 'post'
			) );
	}

	return $request;
}

// doing so may cause the functions like is_home() work incorrectly
add_filter( 'request', 'alter_the_query' );