Zero lag for me all the way through to the '"end". The denosovian permanent upgrade completely breaks the game, as others have said. Another note is that the research point passive bonus is mis-stated on the prestige warning screen, by a factor of 100 or 50 I'm pretty sure. It made me delay my first prestige for far too long, because my 4.5% increase was actually 4.5x I think.
One thing I didn't like was the cost reset upgrades. They feel really, really min-maxy, which is cool the first few times but rapidly becomes tedious. Maybe it's fine, if you put a button on the animals themselves to buy the reset if it's available so that I'm not hunting and tab switching a ton, but... I dunno. I'd have rather seen more synergies.
Still a perfectly acceptable way to spend a couple hours!