There's been a lot of discussion regarding respawns, with suggestions that they don't happen at all, or that they happen after a week or ten days since the last patch. My experience says none of that is true.
I've started a new character and game since that update, but yesterday and the day before was really my first foray into the urban areas near Hangman's Alley and Diamond City. I'd gone to Bunker HIll (looking fruitlessly for Cricket) and then down by the river up to the street that leads to Diamond City. On the way, I killed a group of raiders, a yao guai, three feral mongrels, and a second group of Raiders. The "Pillars of the Community were all unfortunately killed later on). As I passed a point on the street, I killed several supermutants and a couple of their doggies.
Cricket was not at Diamond City, but since I had Hangman's Alley in my quest list, I went ahead and cleared it, set up the radio and dinked around with creating beds an such. After spending the night at that settlement, I set out to head back to Bunker Hill and see if Cricket was there. On the way, the second group of dead raiders was still dead, as were the "Pillars", the mogrels, the 2nd group of Raiders, and the yao guai.
Spent a couple of days at Bunker Hill and related quests, decided to go back to Diamond City. On the way, the yao guai was still dead, as were the first set of raiders and the mongrels. The second set of raiders (and their turrets) were back in action, and I took them out again.
I stopped at Hangman's Alley, then went toward Diamond City by the back way... Ran into the supermutants, alive and well again... but not for long, eh?
The next day, the supermutants were still dead, as were the first group of raiders and their turrets, but the second Raider group had respawned. The mongrels didn't show up again though... nor the pink bear.
It's hard to sort out, but it would appear that respawns are far more random than previously, sometimes much sooner, sometimes not at all (or at least not yet).