The civvy operated ones I see around in the Horn of Africa on UN contracts manage to get airborne pretty quickly. Maybe it helps that they have to pay for the fuel!
Trim Stab, obviously the RAF doesn't pay for its fuel, the oil companies just donate it for free.......
The 'civvy operated' ones aren't J models so you're not comparing like with like, and anyway it's not as if crews loiter around doing unnecessary checks on a whim, they're working through the checklist as provided by the manufacturer. Besides, an extra couple of minutes doing the checks properly is not going to make a big dent on the fuel burn of a leg to Akrotiri for example.