Hi
I have discovered a workaround to the problem (as suggested to me by @disco79stu - Thank you!) that if one selects the parking in GSX when very close to the actual parking, the GPU does turn up in good time. And from the spot view, one can tell that it spawned at the point where parking selection was made and not from behind the aircraft how it does before departure.
So, the problem of the GPU taking a long time to turn up after arrival seems to happen if the selection of the parking for arrival is very far away, as in my case, I normally select my parking just after passing 10,000ft in the descent and before reaching the transition level. This is normally miles away from the arrival airport.
Perhaps this root cause should be investigated and a fix provided.
Thanks in advance.