close tcp-IP connection before php-skript finishes

Hello! I have an problem with on of our scripts, and some caching proxy servers the script produces output, then it does a flush(), After this, the script does a sleep(10) and then it does a db-query without producing html output. normally the browsers get the page after the flush() command but on some proxy servers, the page is forwarded to the browser only after the proxy server has terminated the connection to the apache webserver (after the 10 secs). my question: Is it possible to terminate the tcpIP connection, before the php script ends? (I think this would solve my problem) Any other Ideas? Thank you, Peter Kuppelwieser