I have the same issue with my X5. It just seems like sometimes it wakes up fast and sometimes more slowly.

I have wondered whether this is releated to the problem where the steering wheel does not always come back down to the correct position.

I am hoping the September software update will have some fixes for making sure the X5 wakes up faster and more completely before us "impatient" drivers get the car started and in gear.

I agree with Ferguson...the inconsistency more annoying the problem itself.