Some php code optimizing

Hi!

Hope someone can help me to optimize the following code. I know, I can handle it with multidimensional arrays, but arrays and I are at war…

if ( ! function_exists( 'get_genre_meta' ) ) :
function get_genre_meta(){
	$genres = array();
	$systems = array();
	$categories_list = '';
	foreach((get_the_category()) as $category) {
		$parentCatName = get_cat_name($category->parent);
		if($parentCatName == 'Genre'){
			$genres[] = $category->cat_name;
		}
		if($parentCatName == 'Systeme'){
			$systems[] = $category->cat_name;
		}
	}
	foreach($genres as $cat_name){
			$categories_list .= '<a href="/'.strtolower($cat_name).'/"><img class="systems-list" src="http://www.lost-in-games.de/wp-content/themes/twentytwelve/images/minibuttons/'.strtolower($cat_name).'10.png" alt="'.$cat_name.'" title="'.$cat_name.'" /></a>';
	}
	foreach($systems as $cat_name){
			$categories_list .= '<a href="/'.strtolower($cat_name).'/"><img class="systems-list" src="http://www.lost-in-games.de/wp-content/themes/twentytwelve/images/minibuttons/'.strtolower($cat_name).'10.png" alt="'.$cat_name.'" title="'.$cat_name.'" /></a>';
	}
	echo $categories_list;
}
endif;

You see, I will show in wich categories the articels are. There are categories for the genre and for the systems (yes, it is a games site). But the genres must be shown at first and the system at last. Is there a way to change the code to save resources?

best regards
Myar