At first i planed my levels to be very very big, but i am noticing its not a good idea because i want to use high poly models and if the maps are that big it can be slow... so i think i may divide the map in smaller parts so i can make my models high poly.

Is that a good idea?

PD: I will be using fixed cameras, do you think that will help in the framerate? Is not the same an RPG with fixed cameras than a FPS with fast movements.