Alot of people have experienced, ill just drop it in here hoping for chat devs to see it asap - TC seems to be bugging out.
A connection with TWITCHCLIENT x enabled, regardless of the value of x, receive all HISTORYEND and HOSTTARGET messages any user joining each channel receives, instead of it just sending the info for the user that joined.
Screenshot from my IRC client: http://i.imgur.com/dwOIILj.png
This was reproduced by constantly leaving/rejoining the chat on a 2nd client (browser chat works aswell)
This gets pretty ridiculous for some channels, if alot of people joining, this can easily exceed 2k messages per minute. No rate limiting is applied to these messages, not even the “data received per connection”. This can pose a gigantic problem for certain applications, I guess. My bot, which is sitting in just approx 50 channels, was receiving over 25000 messages per minute when I first found this to be happening. I can only imagine this posing a stability issue to chat servers. I have not experienced any differences between server IPs, event/normal chat or the like, this seems to be a global issue.
Hope that info helps.