I've been doing this route for nearly 15 yrs and it's never been good for any airline. The new-ish Terminal layout makes you very fit by sending you the length of the building a few times. Don't get me started on car rental drop off and the new motorway layout for exit and entering the airport.
But as for fast track, there's been moans about Heathrow "Fast track" (pre-first wing), as for a southern Spanish airport, I've always found them not to be fast at most things! Manana! Manana!
...but in fairness I'm used to the ridiculous pace of life in London!