I've had a detailed look at the Air Asia proposed timings, because I couldn't quite believe they were going to get 5 round trips a week KL-London with one A340. But they certainly are attempting to.
Always 90-minute turnrounds in London, at the end of a 13.5-hour sector. Most turnrounds in KL only marginally longer. Just one stop a week is 12 hours. Planned utilisation up at 19.3 hours a day.
With one secondhand aircraft (ex-Air Canada apparently) this sounds like a recipe for periodic chaos, especially as A340 maintenance will be new to teams at both ends of the route. One diversion or significant dispatch delay and they will be finished; the only recovery would be to cancel a round trip. Unlike short-haul low-costs who have a chance to recover overnight when things go pear shaped, this aircraft just goes on and on at constant utilisation.
I really would have advised in their initial few months, at least, just 4 round trips a week, and a softer schedule.