This has been a problem with the bot for a long time.
The problem is that it waits for the animation to finish before moving (and sometimes even recalculating when it isn't needed).
I know it is possible to do fast mode because hearthcrawler had it and hearthbuddy too. But hearthcrawler died, and hearthbuddy removed it for some reason, maybe because it didn't work all the time and they didn't want to bother fixing it? But it is becoming a huge problem now that more games have a lot of minions on the board.