ScrollZ

ScrollZ is an open source Internet Relay Chat (IRC) client based on ircII. It incorporates many useful features found in all sorts of scripts. The main difference between these scripts and ScrollZ is the size, speed, and low resource requirements – in contrast to most IRC clients extensively customized using scripts, ScrollZ only takes a couple of extra kilobytes compared to the stock ircII client and runs very quickly on almost any machine. This is accomplished by using native  C programming instead of the ircII scripting language. This reduces memory and CPU usage and code tends to run much faster.
See more at Wikipedia.org...