Run function on posts sequentially - php

Question

I have the following (resource intensive) function that I am triggering on the save_post action. It works perfectly when I save OR edit a single post. The problem is that I need to use it when importing multiple posts at the same time. I believe it is running this function across ALL imported (saved) posts at the same time.
How can I use the save_post action BUT only have this function execute on each post sequentially?
function getYouTubeTags( $post_id ) {
// Terminate if post has any tags
if ( has_term('', 'post_tag') ) {
return;
}
$out = null;
$video_id = get_post_meta( get_the_ID(), 'rfvi_video_id', true );
$tag_url = "http://www.youtube.com/watch?v=" . $video_id;
$sites_html = file_get_contents($tag_url, null, null, 700, 7000);
$html = new DOMDocument();
#$html->loadHTML($sites_html);
$meta_og_tag = null;
foreach( $html->getElementsByTagName('meta') as $meta ) {
if( $meta->getAttribute('property')==='og:video:tag' ){
$meta_og_tag = $meta->getAttribute('content');
$out[] = $meta_og_tag;
}
}
if ( !empty($out) ) {
return implode(',', $out);
} else {
return;
}
}
// Add YouTube tags to post
function rct_save_post_terms( $post_id ) {
$terms = getYouTubeTags( $post_id );
wp_set_post_terms( $post_id, $terms, 'post_tag', true );
}
add_action( 'save_post', 'rct_save_post_terms', 110, 1 );