Oh hell... it was -because- of Vsync. Turning vsync off returns it to normal speed. With vsync on, it goes nuts. I'm not entirely sure this is an issue with your game given that, nvidia cards in dual graphics laptops can have certain issues with vsync if the intel card isn't active at all. Still, I guess it's worth being aware of?
It's an engine issue which will hopefully be fixed eventually - out of our hands but at least we know about it and some possible solutions.
It's not an engine issue. It's an nvidia prime issue. Having just spent a day doing terrible things to my system to try to fix vsync in general, it now works just fine in this game.
What I mean is this should be able to be solved on the engine side too since the super speed on some things is caused by features the engine relies on not working right, but I am glad it is fixed for you now! Have fun!