It's IRC, you can run servers for it on plant pots using slugs as bandwith & it'd be no different in performance than if you shouted across the room.

To put it in context if you really wanted to you could run an IRC server on a '96/'97 era Pentium. Hell if you didn't mind it being a tad slow you could probably squeeze a server on a 386, though it'd probably take a month for the machine to boot if anything happened ;)