I have the same problem, and I see that the most in objects rendering (loads late...) and fps drops.
Also, as one that always keeps track of the CPU in the task manager, I can say that in 0.3 my CPU was on average 40%, and in 0.4 it's on 70%.
I guess there's some resource issue, probably with the new AI as some of you mentioned before...
I don't think that the specs really matter, but if you really want...:
I7-9700k
EVGA RTX-2070
32RAM DDR4
And my GTA V is running on the SSD, if some1 really cares...