Can someone explain why early Heisei Phase 1 was so...fluid?

It's something I noticed watching clips of Kuuga, Ryuki, 555, just a bunch of early early Heisei seasons. I assume it has to do with the FPS, but everything seems so...smooth. I can't really explain it, but the way everyone moves feels HD when compared to seasons even just a few years later. Heisei Phase 2 looks pretty standard, and doesn't have that same extreme fluidity