Apparently, energy efficient dishwashers have an energy budget per cycle and will only put a fixed amount into heating water, so getting hotter water into the dishwasher makes a huge difference in performance.
The difference with "primed" hot water is pretty crazy for something that seems trivial. I've also found opening the door and jiggling the racks during the drying cycle also makes a pretty big difference (assuming you catch it at the right time--and use heated dry)
Can also help to run/prime your hot water tap before starting cycle to start off with hot water (in places where it’s hooked up to hot).