I know you recently gave us more time to complete it with 3 stars but I have tried twice on heroic difficulty and it's just impossible. I managed to get my time under 200 but there is nothing more I can cut out. I click through all the talking as fast as possible, I don't even touch any loot from the fights and I use area of effect skills as soon as I can. There is nothing more I can do and I can't get my time under 198.

Most missions have an easy time limit, you don't have to do much to finish on time. Some missions however are (nearly) impossible, especially ones with lots of conversations in them, for some reason.

probably not or not for all classes. it's not that the classes were really balanced. I lag a lot so I'm not even trying. I tried the game from a super new supercomputer of a friend and it still doesn't work like the other games. he was like O_o you want to spend 1000 euro on a computer for this? lol. I suspect it might be about local internet connection and I can't influence that no matter what speedy computer I buy.