Simple Free Chat program over Internet

I asked this same question for just a LAN, to  text chat without overhead.  Kutyi came up with a great program called TONIC -- see that question for background -- https://www.experts-exchange.com/questions/23571639/Simple-Free-Chat-program-between-computers.html.

Now I need the same thing, but over the internet -- NO overhead, no video, no system delays, no phone dialing, just a free simple  program that does nothing but text chat, it sits in the system tray, and pops up a message when needed.

I realize it is harder over the internet, which is why Skype etc have servers to keep track of people.  But Skype, iChat, AIM, MSN messenger, vonage, and you name it -- they all install modules that poll the internet constantly (or require a login to their site, like ICQ, AIM, MSN, and so forth.)  All of this bogs down the computer, causing delays in typing, etc.

I realize this is probably impossible to get any more, but I am looking for a text-only messaging program to another person on the internet with essentially no overhead.  Before you suggest M$ software, or the major programs, PLEASE read the previous question, to realize, I have tested all the big programs, and they take too much system resources.

If anyone knows of a simple program that sits in the system tray, does not involve login to a website, and does not take any significant resources polling the internet too frequently, only that recommendation will get points.  No programs that like to MS office modules, please !!   The OS is XP.  Thank you.