homepage loading too slow

There was a thread on wp-hackers in December which could be related: Avoid query_post on frontpage on wp initialization. You may give Sergey Biryukov’s code a try:

I was able to cancel the initial query with this code in the active theme’s functions.php file:

function cancel_first_query() {
    remove_filter('posts_request', 'cancel_first_query');
    return '';
}
add_filter('posts_request', 'cancel_first_query');