I recently saw an aircraft following some distance behind a South West airplane ( 2015 livery ) and the first thing that struck me as interesting was that it seemed to be moving faster than the South West airplane. And several airplanes fly in the same flight path above me and never have I seen one that seemed to be moving quite as fast. It didn’t look military as it was painted blue and white and had both engines on the back of the plane on/near the stabilizer. The other thing was it appeared to have a strange shaped object on the wing tips of each wing. ( Sort of like the Learjet 24 but it was a bit high up and maybe I saw it wrong).