[Stevvo]

In the recent versions of the simulator, most cockpit displays render in less than 1ms per aircraft. Early versions were a mess; the cockpit displays were not only slow, but also entirety fictional. At some point Microsoft hired WorkingTitle, a studio of web developers with no C++ experience, to optimize and improve the cockpit displays. They also wrote that autopilot code you mention. It's not "the autopilot" however; the PID controllers that fly the plane are on C++ side, in JS are huge amounts of input related code to make it behave like a Garmin or Airbus system.