It may very well be something in the scripting engine. There was a decent amount of activity in two of the channels and no issues so far on 7.45 (main) or the 7.46 (testing).
Only script in testing one is a startup one that makes two connections to the twitch server (two different names and different set of channels). Also starts up a timer that updates the titlebar with the current mIRC uptime. Uptime thus far is almost 16½ hours.
Have the same performs executing (enables additional info from the server), so everything is essentially the same except the lack of scripts.