I have D90 (full shutter lag 0.2 sec) and I am looking for fast focusing lens.
How much is full shutter lag with:
Nikon 16-85mm lens
Nikon 18-105mm lens
The speed at which the lens focuses at is 100% independent from the shutter lag which is specific to your camera body.
Both of those lenses use the same mid-grade AF-S motor, you won't notice much, if any, difference between the two.