Process batch code

I've a php script allowing people to add a new article in the database.

Once the article is inserted, the user who are interested should
automatically be contacted.

The second script works fine, but they are so many users than firing it once
the first script is fired takes too long for the user who inserted the
article.

It's there any way from a script to execute an other one without waiting for
the result ? I mean my page insertarticle.php should call contactbuyers.php
without the need to wait the contactbuyers.php to finish.

Thanks

Bob