There should be a period of time between the flaps being lowered and the set angle to complete the maneuver. In the P-40F, when the flaps are lowered, the nose lifts instantly, without smoothness or delay. I think it's a little weird that this is not quite in line with the aerodynamic characteristics, feel in the operation of the action game aircraft.

Can you please confirm if you are lowering the flaps in stages or fully open immediately?

lowering the flaps in stages. 

Aerodynamic effects of moving the control surfaces including the flaps are directly connected to the physical position of the surface in question. 

They deploy quickly so the effect is quick in its application, the key here is what speed you are deploying the flaps at, if you deploy them very fast then the effect will be enhanced by the CFD 

Thanks for the explanation, I'll verify it again.

 

Best practise is to put them down in stage one, then give it a short while to stabilise, then 2 then 3 and then 4 (4 should really only be under 150mph ideally) 

If you deploy them fast (say under 10 seconds between stages and at too high an airspeed) then you will get a fair knock in pitch as the profile of the wing has changed rapidly