justanoldmuso,
You are not correct on the LAG.
Here is a very basic example for you. Kontakt has a dozen of phrase libraries (Session instruments). These phrases are similar to real tracks - they are also recorded (audio) performances. They respond to tempo and chord changes on the fly. Several of these Session instrument instances can run simultaneously and you can control them live using MIDI keyboard as controller.... On Windows computer.
They had been able to do this for quite a few years now. Since early 2018 to be exact.