Use .htaccess to prevent feed access?

My server cpu load spikes like crazy when my feeds are accessed, to the point of making the server unresponsive. I use WP (multisite, path-rewrite not subdomain) as a CMS, so I am not terribly interested in the feeds, and I’d just like to turn them off.

Is it possible to rewrite the WP multisite .htaccess rules to prevent */feed/ from ever being accessed?

I tried the following functions.php fix, but apparently the hooks kick in too late to prevent the spikes, so I’m thinking .htaccess is a higher-priority kill-switch.

/**
 * Disable feeds
 */

function fb_disable_feed() {
    wp_die( __('No feed available, please visit our <a href="'. get_bloginfo('url') .'">homepage</a>!') );
}

add_action('do_feed', 'fb_disable_feed', 1);
add_action('do_feed_rdf', 'fb_disable_feed', 1);
add_action('do_feed_rss', 'fb_disable_feed', 1);
add_action('do_feed_rss2', 'fb_disable_feed', 1);
add_action('do_feed_atom', 'fb_disable_feed', 1);