The chat server has been upgraded to use HTML 5 WebSockets instead of HTTP polling. For those who have no idea what either of those are, "polling" is basically asking the server every second, "Do you have anything new for me?" WebSockets are a permanent connection, so the server can just send any new information back to you as soon as it gets it, instead of waiting for you to ask.

The chat server needed a rewrite anyway, since it had only had minor improvements since it was first implemented in 2001. The code is much better organized now, and is easier to maintain.

What does it mean for me?
Honestly, not a ton. The chat room looks almost exactly like it did before, except that I removed the rooms feature (which was largely unused). I'll probably add it back eventually. Other than that, it will function pretty much like before.

If you're viewing it on mobile, it should work okay. The keyboard takes up half the screen, which is a pain when you're typing. If you're just viewing, it works pretty well.

Since the old chat server used HTTP polling, one of the side effects was that if lots of people got in chat, the site slowed down somewhat. The new chat server runs pretty much independently of the website, so it should not have a significant impact on the site's speed.