Well you didn't tell me much I didn't already know, simply pointing out 'issues' like it says to : P
The AJAX calls may not be that load heavy now, but they seem pointless to be that often at least, the page itself said to make suggestions about it as well.
As for IRC, over half a million people daily are logged across public IRC networks, it may be more than 20 years old but it's still stronger than any other chat protocol around really, not to mention easy to use across platforms and more so easier than forums to give people support in even (Tis why even modern games have IRC support channels, some even have IRC clients directly integrated into the games).