Airliners cruise between 33,000 and 39,000 feet. Most business jets are certified to 45,000 or even 51,000, and we usually fly at 41,000.
Up there you are above nearly all weather and away from the busy airline levels, so controllers give you direct routes. A shorter route means a shorter flight.
The cabin is pressurised to the equivalent of 6,000 feet — lower than an airliner — so you arrive less tired and less dry.
Empty legs, explained
The ten-minute terminal