Have you been in the situations I stated above though? Act 3 is really the only place the game struggles for me, going across the battlements raising catapults and lighting signal fires in a spell heavy group can make it chug a little and the bridge before the seige beast chugs like crazy, everyone I've played with get's it at the same points as I do so it's definitely engine or company-side, somebody I play with stated it could be the servers not keeping up. Although it does kinda make sense, I'm not sure how it could cause stuttering.
It's more peak time than say, 2am-9am. Some people work night shifts, have few days off or no job at all, it seems the 9-5 bracket get the cushty jobs and the consideration with stuff like this over here

why not do the maintenance through the night like they do in America.
I wonder what would happen if they didn't perform maintenance though, is it really neccesary or is it like a user running CCleaner often out of habit, hmm.
I noticed the AH was down for quite a while last night after the servers came back up, quite a few million worth of plans I found boosting a friend disappeared when placed on there, thankfully they came back.