wp_insert_post() getting slower the more posts

I found the solution by the comment from birgire what tells to use
wp_defer_term_counting() as follows:

    if( ! $errors ) {

        // Set wp_defer_comment_counting();
        wp_defer_term_counting( true );

        foreach( $lines as $line ) {

            // Import post
            $args = array(
                'post_title'    => $new_vipost_title,
                'post_content'  => $new_vipost_content,
                'post_status'   => 'publish',
                'post_type'     => $vipost_type,
            );
            $post_id = wp_insert_post( $args );

            update_post_meta( $post_id, 'vimport_key', $import_key );   

            // Set term if isset
            wp_set_object_terms( $post_id, $viterm, $vitax, false );
        } 

        // Set wp_defer_comment_counting( false );
        wp_defer_comment_counting( false );      

    } else {
        $_POST['errors'] = true;    
    }