We have been trying to develop an HTTP chat room in PHP for a while. HTTP is not a good protocol for chatting but it is firewall/proxy immune, can use the potential of PHP and there's no need for Java Applets. We have had two main problems with the chat room: first since IE doesn't support the PUSH method, we needed to make it a "pull" application, (the client refreshes itself) which is unnatural for a chat application. We decided to make the client refresh time variable, the server will generate the refresh time as a function of the number of messages received in the server in the last x minutes. The second problem was deeper: since the idea is to refresh the client we would need the server to send all the messages each time, we observed that this implied heavy transfers and our benchmarks in a simulated simplified chat room model showed that this was the main cause of delays in the chat. This article deals with that second and deeper problem.