Did you see where I said two separate circuits? They are both 20A gfci outlets in my kitchen, less than 5 feet apart, ON SEPARATE BREAKERS, and the 10/3 cabling I chose is rated for much higher current than they will ever see in my setup. I fill my kettle with hot tap water then I hit the start button and measure out hops, mill my malt, etc. while it heats to strike. When it reaches strike temp it beeps to let me know and precisely holds that temp till I'm ready to mash in. My step mash routine takes the temp up to 170 over the 90 minute total mash time, then I raise the bag and switch to boil mode and hit start. It reaches a boil just in time for me to finish dealing with the bag, seems like about 20-25 minutes. The kettle is insulated with three wraps of reflectix, but it really didn't make much difference in heating times, it's mostly to hold mash temps. This setup runs plenty fast for me, you are the one who is mislead.
Next weekend when I'm brewing a batch I'll use a stopwatch and benchmark every step of the process, just for argument's sake. I chose 1500w elements to leave ample head space on the two 20A circuits, and was dreading the performance that decision would cost me, but it far exceeded my expectations and I'm really glad I went that route. I run a continuous recirc throughout the mash while stirring frequently, and even with the heat losses through the tubing, fittings, pump, etc. it still has plenty of power, is very responsive, and boils vigorously. Overall I'm thrilled with the performance of whole system.