I have it down to 30 seconds, 15 minutes if I take my time and join the monastery.
I did not count but since I entered monastery and accepted new name, I walked few steps in the atrium, then random monk came up to me saying I should not have that weapon in here. I had halberd in my inventory which was not transferred to my safe chest since it is not allowed by simple buttons to store it in inventory but just keep in hand, so even when I trick the game to put it away, guards and monks especially say I have weapon drawn. So I was expelled, sneaked in by the back door, read some list of new novices. I guessed which of those might be my target. Found him in the big room with others sleeping, stabbed him and ran. Quest updated. Never outsmarted game like this before. I never experienced that awful questline many seem to be bothered with. I was actually looking forward to it but then I found the short way, why would I bother with self punishment.
Once you know who Pio is (after first play) you can clear it as fast as your fingers can knock out/kill him.
But you lose Libri Prohibiti, Scattered Pages and Nasty Habits side quests…
actually in my third playthrough I helped pie guy escape but I ramped up lockpicking way before I reached needle in a haystack and already stole the books, I would like to complete those side quests but monastery is painfully boring. Next time i’ll have to grab all those pages along with the books, nasty habits is rather simple…it wouldn’t be so bad if warhorse didn’t give you a 2 second task and several minutes of idle waiting, constantly time skipping through the day kills the whole experience.
on my second playthrough I googled who pious was, and killed him forgetting that I DIDNT have stealth 5, so I stomped on his face, and woke the whole monastery they’re yelling Guards!! and as the guards came in I ran out and escaped the monastery, wondering why I didn’t get a quest update, I forgot to take his dice, and had to break into the rattay morgue to get it. LOL